Though I rarely post here, I thought I would add some thoughts to the discussion as I have a Linhof Techno and an IQ180. The combination is new to me (though I have had the Techno for awhile):
First, I was previously shooting the Techno with a P65+ and the Kapture Group sliding back. Focusing on the ground glass, the two widest lenses I was using were the Schneider 47 and the Rodenstock 28. I often employ tilt and, combined with stopping down to around f/11, I was able to consistently and confidently nail focus nearly all the time.
With the IQ180, I decided to ditch the 47 and replace it with a Rodenstock 40mm - which I just received - due to the limited movements and severe color shift associated with using movements on the Schneider.
On the IQ180, I am nearly always using LiveView to focus - particularly for tilt. In fact, I recently purchased (but have yet to receive) a fixed plate back to replace my Kapture Group sliding back. For my purposes, LiveView is such a dramatic improvement that I think I'd prefer to save the size/weight/hassle of the sliding back (shooting almost entirely landscape photography with this setup, so weight matters when hiking).
LiveView on the IQ180 combined with the Techno is excellent. I carry a vari-ND filter for bright light, though I often do not need it. The biggest downside to this setup is that i get a fair amount of noise in the shadows if I am using LiveView for a long period of time and then taking longish exposures (2-15 sec) - apparently the back really needs a little cool-down time. Of course, I am in Arizona where the air doesn't cool down a great deal this time of year.
I previously had a plate camera (Cambo RS). I definitely prefer the Linhof, particularly because of the ability to Tilt built into the camera vs the lens. My biggest complaints about the Linhof are:
1. Gearing - I'd prefer finer gearing. It requires very small movements to nail critical focus.
2. No rear tilt - though you can duplicate rear-tilt results via some tilting, shifting and camera body adjustments (tipping the entire camera back form level).
Overall, I'd highly recommend the combination for slow, methodical capture not dissimilar to 4x5 work. Compared to the RM3Di, I think you are getting something that is ultimately similar, though less expensive (due to the simple lens mounting). The Arca is better on fine focus, the Linhof "feels" much more like a 4x5 camera in action and thus may be preferable to some.
Hope those thoughts help...
Dave