Hello,
I used the Leaf AFi-ii 7 for a very long time and it was excellent - I made superior very large exhibition prints from it. I traded it in for the Aptus 12. The files are heavier of course, but brilliant if you need the incredible resolution. I hope to continue using this system forever - there would be no objective reason to replace it (save for lack of parts). The camera is great, the lenses magnificent, the back unsurpassed in image quality. Maybe some of the newer Credo or PhaseOne backs are easier to use, I wouldn't know, but I can't imagine that they produce better results. The camera, if you didn't know it, is no longer made. Currently the only service center I know of is Paepke in Germany. Maybe there will be another soon ... ask Eric Hiss who would likely be the first to know. He is the best source of information for this system.
Neil