Siebel, Your work is great and the architecture work is obviously carefully composed. So I wonder, how do you do it without seeing through the ground glass? I find that often the slightest change in perspective will completely make or break a composition, so I rely on the gg. And I just like to see the image through the lens, and view what's outside the frame as I compose. I use an Alpa and switch between gg and back, which is slow, anxiety provoking, and admittedly not much fun!I would be surprised if ANY of the tech cam makers invest further in the groundglass area.
Most are holding their breath hoping for the next MFDB frontier to open up - true Live video. Once we have this feature, groundglasses and to a lesser extent, viewfinders become obsolete.
As it is, I very rarely use my viewfinder, preferring instead to view over the top of the camera and shoot a test frame, even when shooting handheld.
The next accessory I want is a 2 way spirit level that I can view from behind the camera, without a viewfinder (ATTN Team ALPA. I hope you are reading this!)
I'm tempted to try using a mat board cut out for a framing device and then try to fine tune with the back's lcd, but I'm doubtful... I may just end up using a dslr when I have to work fast, and hope live view comes along some day!