That "Don't modify your gun or you'll do time in the Verticle Bar Hotel" arguement has been around for a while, and I think in some cases it may have merit, depending on the nature of the mods and how lousy a lawyer you have. I've only ever heard of one guy who had trouble that way, an IPSC shooter who used his race gun to kill an intruder in his house, and he wound up settling the civil case out of court.
The author of one of the defense books I read recently--it might have been Walt Rauch in
Real World Survvival--had a list of mods that might get you in trouble. Basically, if it makes the gun more reliable, safe, or accurate you're OK. If it let's you shoot more, faster, then you might be introuble.
My father in law has an SP101, and the DA trigger pull is almost too much for--it is too much for him, or my wife. They can handle the SA pull, although his friend can't. (Hey, at that age, I refuse to call her his girlfriend.
) A Wolff spring kit is in (and on) order.
Also has trouble seeing the sights--we gave him some of that sight paint (for got the brand
), and am loking for replacement front sights. The Hi-Viz folks tell me "We're working on it...", but Trijicon has a tritium front.