I have a Rotary 2-post assymetrical lift and thus far it has been problem-free.
I planned for the lift when building the house and it sits on a footer that is 8" thick. Very solid, and easily lifts the small race car, or my 6000 lb Touareg.
I park my S4 or Touareg in this stall every day. Occasionally I will use it as a parking lift and keep a car up high while parking another under it.
-Will