I love the idea of the SL66, but unfortunately they seem to present one problem after another.
I looked into it, bought into it, because at the end of the day I did not find evidence to support SL66 problems any more than Hasselblad.
I can also say SL66 mostly feels great, works smoothly, but it's not that perfect and as any camera needs time to adjust to it.
Today after loading film in the magazine, attaching it to camera, removing dark slide (so technically back was locked onto the body, I managed to disconnect the back from body, which is not suppose to happen. All I can think of is I must not have had it fully attached, but enough for dark slide to come out. Engagement of back to body on SL66 is on shallow side, so I think there is a point where dark slide will move, but back can still come off. So I need to be careful from now on to ensure back is solidly on body before pulling dark slide. What happened does not bother me, but it does show it has its flaws too.
Second little nugget is the focusing knob. It sticks out so far out, putting in a bag is not what any other system MF camera. The knob makes the whole body much wider and the only flat side is bottom. Compare to Bronica or Hass, it's very noticeably different.
Still, SL66, in my book, feels much better than Hass. Mirror action is also smoother than in Bronica EC, otherwise I would have picked EC over SL66b for handling.