This thread is will probably inflame many readers but I'm talking from my own personal experience.
11 months ago I decided to upgrade my Hasselblad H3DII (28mm, 35mm, 80mm, 50-110mm lenses)
Hasselblad's distributor in Australia is a joke and had been nothing but rude an arrogant since purchasing my H system. To make matters worse, when I asked about testing a H5D 50C WIFI I was told there were non in the country but that I could purchase one and return it if it didn't suit my needs. Apart from RIDICULOUS, I was financing the camera and therefore this wouldn't have been possible.
Phase One appeared was another option and has very good support here in Australia however their 28mm is an old design with mushy corners and so was not suitable given I shoot interiors and architecture and need a good wide angle.
Pentax has the same distributor as Hasselblad and surprise surprise, there were no bodies or lenses in the country to test!
This left Leica... with the promise of, (and I quote) "purely digital camera system (and was) built with the precise needs of professional photographers in mind" combined with "extreme robustness, excellent imaging quality and perfect matching of all its components" I decided to give it a test. I was able to borrow a body and lens and the customer service seemed exceptional.
There were a few quirks and niggles that I thought I would get accustomed to, or that would be ironed out in future firmware releases so I set aside my existing line of Hasselblad lenses and dumped $85,000 on a new Leica system!
The problems began in the first month. The camera is unable to focus accurately. I recently tested the 70mm lens on a black can of deodorant on a white background. In 16 frames the camera returned 6 different distances ranging from 1.5 metres to 10 meters. The actual distance was closer to 3 metres.
The camera has been back to Germany 3 times in 10 months for checking. They assure me it's within technical specifications but I continue to send them examples of out of focus images. They have also advised me the lens barrel markings and LCD distance should not be used to set focus but instead live view should be used in all situations in which focus is critical (I would think for any photographer focus is critical for EVERY image).
Throw in a battery charger that indicated batteries were charged but when I began a job the camera indicated ALL 3 batteries had no charge. I had to leave the shoot to go home and collect my Sony A7RII to complete the job.
Confetti noise, weird blobs on the sensor, a firmware update that crippled live view for 4 weeks and a 30-90 zoom that was mushy in the corners are amongst many other problems.
I'm now trying to terminate the contract and buy something I can rely on but they have so far refused to accept there is a problem with the system saying the camera is operating within technical specifications... Yeah... like the M8 was operating within technical specifications with it's clear IR filter problem.
The number of megapixels and crop (3x4 v 2x3 format) are subjective matters that depend on one's shooting style and the type of job you're shooting. Having a camera you can rely on is CRITICAL regardless of your style or assignment.
When you nail a shot it looks beautiful, but I can't place any faith (or my career) in a camera system so riddled with bugs, brought to you by a camera company more concerned about releasing titanium versions of its Leica Q, Leica M's with ping pong rubber grip and limited edition red coloured M lenses.
I've read many other horror stories so would be keen to hear from other S system users about their own experiences.
Sorry to hear what happen to OP.
I noticed S camera AF problem as soon as I bought the system. Basically, it has real problems to deal with fine detail focusing subject such as small leaf, grass etc at long distance for those situation, I get "consistent"AF fail. For general use, I also find reliability issue like OP report. For same subject, I don't get the same AF results. Even for high contrast stuff(you would think), I still can get AF failure sometime. I also remember the AF system has different sensitivity to vertical or horizontal subject suggest AF point is not cross typed.
As Someone early reply in this thread suggested, I usually just manual focus whenever I have enough time to do that. If not, I always virtually check AF before capture. for critical shot, I also make sure focus after capture. (I was burned once to find out that many of my shots from Zion was off even I though and AF point is well defined)
I have used S2 and S006 and S007. I sent my S2 for clean sensor and S006 to Leica just want make sure my unit is in spec. (I expect to be told it is even though I see lots of problem) In the time of sending the units. I got loan units of S2P and S007, The problem is there for every units I can hold off. The reason I know it is in spec because it can lock focus if you really give it well defend target. and I know it is in spec because I know spec is sloppy.
I was hoping S007 will improve upon this problem, but it is not. And focusing distance scale in LCD is a gimmick at best in my field use. For same target,(Tree in distant) I can get all kind of reading. It is not a surprise as AF doesn't know where the target is at, how can it report good results. This directly turn off all my S007 desire. I prefer 006 color anyway.
I especially hate it AF implementation of hyper focusing. I notice at small aperture, if camera detect the focusing point is within DOF window, it will not re-engage the focusing. It is really annoy that I have to Wide open the aperture to re engage the AF. This is a big flaw to me as no way the camera know what is optimized DOF window I want to cover and where is my main subject I want absolutely in focus. Plus, I have no idea if those distance is trustable anyway. This pose a huge problem in field for me. For landscape, you will assume the lens focus at WO so that you can choose hyper focus point yourself to cover DOF by shooting at small aperture but focus WO. this way you can use best suitable aperture for the IQ. (S glass is capable shoot landscape WO at low light if no DOF need cover) but many case I have no idea where is the camera focusing point if it is not re engage the focusing.
For me, I don't have any other systems approaching the file quality I can get from S glass and sensor combined.(I test pretty much all 35mm system) The CCD color are beautiful, 2nd to none and the OVF are the best. Shooting experience is nothing can touch it. Operating at low light and cold weather with glove is awesome. All this overcome the flaw for me, especially I personally really enjoy manual focus shooting even with 35mm system. Also I have to say AF seems works fine at portrait distance say 2~3m for 70mm, 1~2m for 35mm or 2~4m for 100mm most of time, as DOF is bigger enough to overcome loss AF tolerance. closer than that, I mostly manual. It is a case by case scenario judge by experience.
If you set expectation to be about AF performance of old medium format film or Digital, you will probably be fine. If you compare S to modern Canikon, you will for sure be disappointed with its performance.
So, I have a feeling replace units won't solve the issue you are seeing. I have handle over 5 S unit range from S2 to S007. I can always make it AF fail if I want, I know it is mostly a technology limitation other than a single event.