bicycletricycle: Funny you should bring this up. I had 2 SL66 bodies, 3 backs and 3 lenses. Just today I came across some Ektachromes shot with the SL66. Some were with the 80mm Planar, some with the 50mm Distagon. I was blown away. I too sold my kit to raise some cash, and now wish I still had it.
I can highly recommend the SL66, though the backs sometimes need CLA as they have a tendency to get a bit out of whack.
I LOVED the bellows extension, tilting stage and reversible lenses. I don't know if the lenses in shutter can be reversed for macro (I doubt it), but for me that feature was invaluable for a lot of the work I did with them.