Yea, it's a concern of sorts - it's a shared garage but the two guys I share with are both great about keeping stuff locked up. After all, they have expensive stuff in there too (my one neighbor has a Harley Road King, the other has a BMW 3-series and a beautifully-restored 1970 El Camino with a 502 engine and a crapload of mods - he's got about $60k into it). The guy's a former Navy SEAL and U.S. Marshall too. Not the kind of guy you want to screw with.
So I think a lift would be safe. Plus they'd have to figure out how to get it out from under the car. Plus I have CCTV monitoring in there anyway.
Anyway, I'll look into that lift - that sounds like it'd make wrenching sessions a HELL of a lot simpler - especially for the sort of things I have coming up (an engine swap and an oil pan gasket replacement - ugh).