I dunno about that. RV's are very, very simple. I would think that in a 4-6 hour prebuy, you could check all structural attach points, check everything in the control system, check the overall construction quality of the airplane, and check everything that has to do with the engine and fuel delievery system. IMO, those are the things that could get you hurt, unless you wanna take the bird IFR before the avionics have proven themselves reliable...
I *think* I'd feel better about the general condition of a 5-10 year old RV than a 30, 40, or 50 year old production airplane. There are sooo many things that can go wrong over that time period. Non-reported damage, poorly repaired damage, corrosion, etc. etc. etc..