THE FINAL VERDICT .... for me
for now
Stick with native Sony Zeiss Lenses:
I just got my 55 FE and looks great. Light, fantastic wide open, no adapters, AF etc. etc. Along with the 35FE, it is a great kit and I will patiently await a 21 or 24 in this line.
Here's my rationale:
1. There appear to be several issues even with 50mm M-mount lenses - Diglloyd just posted some samples with the Leica 50 Lux, Nocti, Cron ASPH and Zeiss 50/2. All appear to have issues of one sort or another. For the money and hassle of an adapter, not sure it is worth it.
2. If you already have these lenses, then by all means, the $300 cost of an adapter is no big deal.
3. DSLR lenses appear to work better, but negate the size advantage with the size of the lenses themselves, and the relatively large adapter needed. Again, in my case, I just got the Novoflex NikonG/Nex adapter and $300 is no biggie for the flexibility of using Nikon glass in a pinch. But I would not go out and buy DSLR lenses for this purpose. I'm sure there are others that have older and smaller MF glass where this may make sense. Also lenses highly specialized lenses like the Canon 24 TSE II have similar appeal for various folks.
4. I do believe there is a lot of RAW file cooking going on in camera. This is not true just of sony, but for all manufacturers. One of the reasons for the success of the Sigma Merill (the fixed lens ones) and the Sony RX1/RX1R is that the manufacturer has far more control of the full image processing workflow. To further this cause, lens profiles etc. available in C1, LR and other RAW converters further augment this. However, this is only possible when manufactures work together with access to each other's technologies. Again, this cannot happen in an open-ended model such as when using any 3rd party lens.
5. The only exception to the above is tech lenses and tech cams with MFDBs. In this case, I think the lens designs are so basic and pure that we have workable solutions, BUT, even in this case, we do a lot of manual processing with LCCs etc. to get the final result.
6. If Zeiss/Sigma etc. release native FE lenses it is likely that LR, C1 and other RAW processors will have lens profile support, even if Sony itself does not provide the additional "cooking" in-camera. With Zeiss, they might. If this happens, then we will have an alternative MF set of lenses for the FE mount. Even better would be if Sony white-labels/OEMs the A7/R to Zeiss for new IKON, and we would have a great platform with native Zeiss MF lenses.
7. For me, this was a small go-to kit for casual work. In keeping with that, I think FE native lenses make the most sense.
So there it is. Of course, this might change, but I though I'd share my perspective since I started this thread, and several people have contributed so well.
Notwithstanding any of this very rational thinking, Guy is supposedly getting his A7 today, so he could re-ignite the arms race all over again