I have a ShopSmith Mark V Model 500 (the base model) that my dad bought in 1980. He gave it to me a few years back, because he decided that his Craftsman RAS was sufficient for anything he'd need to do.
The reason I bought my BT3100 is because the table for the table saw setup is very poor. From the looks of it, they've improved it considerably in the 20+ years since mine was built, but I couldn't justify the $900 to upgrade to the current model 520 tables and fence versus the $299-10%=$270 for the BT3100.
I still have it and use it for:[list=1][*]Veritcal Drill Press (very good)[*]Disc sander (pretty good)[*]Lathe (very good, but I've never used another lathe, so I have nothing to judge against)[*]11" Bandsaw (OK -- kinda small, but does what I need it to)[*]Drum sander (OK for a non-oscillating sander)</ol id="1">I also have the parts to use it as an overhead router, but the setup scares me, so I don't suspect it'll ever see use as a router. I haven't had the need to use the horizontal boring setup, but I can see where it'd be useful, and would probably do the job just fine.
Nutshell: If you can get one for cheap ($0-$600), and are short on space, it's a viable option for a drill press, lathe and disc sander. I use mine most as drill press.
The real cool thing about it is that I have a variable speed drill press (no belts to move!) and you have to pay a good amount to get a dedicated unit. I think the same thing goes for the lathe.
BOFH excuse #360: Your parity check is overdrawn and you're out of cache.