Yesterday, when I returned from a photo shoot, I pulled my camera bag out of the car, and it opened. (It was my fault). My 70-200 and my 5D III with a 24-105 attached fell about 2 feet onto the concrete floor of our garage. The filter on the 70-200 shattered. Fortunately, my wife was out of earshot.
The 70-200 obviously landed front-first. The camera had a mark on one corner of its L bracket, and there was one on the filter ring, so I can't tell which end took the worst of it.
Once I stopped hollering obscenties about my carelessness--which took quite a while--I tried testing the equipment by putting a detailed target on the wall and checking for center and corner sharpness. the target was small, so this meant shooting at a close distance. The camera seems fine. The 70-200 showed no signs of damage and was sharp in every section I examined. (Quite amazing, as this is the second time; the first time, a surprise gust of wind knocked over my tripod, and the lens hit hard enough that the filter ring on the lens had to be replaced. There was no other damage that time either.)
The 24-105 (first generation) is harder to evaluate. It showed modest softness and CA in the corners when shot wide open, but those of you know know that lens won't be surprised, and I have no before and after comparison.
(You might say: an opportunity to replace the 24-105 with something better. I have considered 7 alternatives--the two 24-70s from Canon, the 24-70s from Sigma and Tamron, the 24-105 from Sigma, and Canon's second generation 24-105--and none seems enough better to be worth the cash or the sometimes considerably greater weight.)
Our local, very good camera repair shop has a one week wait for a test and estimate and 1-2 weeks more for a repair, if needed.
Anyone have any suggestions about other tests I might run myself? If I see any sign of functional problems, I'll take it all in.