So I finally got my own Linhof Techno.
I started with a simple Rodenstock 35mm Apo-Sironar Digital, I probably will change it to a Schneider 35mm XL, but both are non-retrofocus so they should have very similar look on the ground glass. I also have the Schneider 47mm XL.
The 35mm is probably one of the most difficult lens there is for this system (if not the most difficult), since the shorter focal lengths are retrofocus. I found it easier than I expected to focus it, I do not feel that I need finer gearing or finer grained GG. I'll do more detailed testing of this in the future though. I only had a 5x loupe, but I think a 10x will be perfect for critical focusing. There's no need to remove the fresnel for critical focusing either, that's great.
Anyway, while focus control was better than I expected, the dimness of the ground glass was worse than I expected. I have Linhof GG and fresnel, and a lighthood with magnifier.
It is about equally bad at 35 and 47mm. In an indoor scene when it is not extremely bright, one simply cannot see the whole scene at once. You see a bright spot where the light rays are coming dead on, so if you want to look around you have to move your head around to make the light rays fall straight in your eye. The fresnel improves it a little but not by much. With the light-hood and magnifyer on it is difficult to bend the hood enough to get the magnifyer in position so you can see into the corners.
Only seeing a small spot it may be hard to understand what you actually look at, but since you have your head in the direction of the light you just need to take a peek past the camera to see what the lens looks at in that direction. So it is indeed possible to compose images this way, but it is a bit cumbersome. It helps being a masochist. I expect it to be easier outdoors though, haven't had much time to test it yet. A focusing cloth makes a big difference too it seems.
The obvious solution to this problem would be to have a special wide-angle fresnel. Linhof actually have the fresnel separate, so it can be removed and another could be easily and quickly inserted. Problem is that Linhof only sells one generic fresnel, at least so it seems from the price list I have.