Surfer,
I bought my Thule as one of a pair, advertised on Craigslist. Cheap. The thing to get is one of the 'old-school' models now being abandoned because autos increasingly have no drip rails no more. Otherwise, the model of Thule is not particularly critical. No expert knowledge of the Thule line here, but it seems the only other likely variable would be the length of cross-bar, which could conceivably be too short to span -- unlikely, as the top of the top is not so wide -- or too long to be convenient, also not so likely to be much of an issue, plus I imagine it would be susceptible to alteration by hacksaw if desired. My bar is from a Subaru wagon and could be a foot or so shorter and still work, but does not protrude beyond the overall width of the car.
I know there is a sort of 'hi-boy' model in the Thule line which just stands the crossbar up a few inches relative to the regular models; this would be of little concern to us in our application unless you need to count every inch of clearance in the hoisted position. That is, when one leaves the top hoisted for storage as I do, the taller mounts would leave the top a few inches lower when hoisted to the maximum. [Walter has issues negotiating my garage space when it's up there, as it shares ceiling space with structural members and the garage door opener, and Herr Klatt is just plain tall. I, on the other hand was never over six feet and have lost three or so inches somewhere in the last decade -- apparently due to rough handling in times past -- and this is about the only situation I can think of in which it is of any advantage at all.]
On the subject of jerking with electric-powered hoists, that is mediated in my rig as a happy side effect of having added a traveling pulley from which the Thule crossbar is hung. I used it because it helped me locate the point of pull where I wanted it as well as spreading the load to two structural members in the ceiling for the mount points, and it also reduced the rate of travel by half, which I like for those final moments of mating things up. The side effect is that it absorbs most of the 'bounce' that the on-offing of the hoist drive can generate in those last critical moments in the mating process. [cough. ahem. um, sorry.]
When it came to attaching that pulley to the Thule crossbar, I wasn't comfortable with concentrating all the stress on one small point, and especially not when weakening that same point with a hole. I started planning to wrap the area in a sort of sheet-metal diaper/sling and fasten to that, but finally did just drill the ~8mm hole for an eye-bolt and made myself feel better about it by sliding a ~18" length of square steel tube over that area (with another through-&-through hole for the eye-bolt) so the stresses get spread out over a much larger area. [That steel stock is heavy-duty stuff, so it's overkill, but simple, cheap and effective; the Thule crossbar is probably the best way of securing our tops, but that single-point concentration of all the stress is a worrisome weak spot.]
I covered the span with a sleeve of tubular pipe insulation as insurance against damage from contact; possible overkill again. The Thule's are fitted with locks to deter their theft, which we probably won't use, but if you're planning on somehow utilizing it, hang on to the key; the key blanks for those locks are hard to find.
