MY G5 had the issue were the cord came out of the braid and slowly twisted and bent. It actually started at one of the bends from when it was original packed, but it lived for well over 3 years before the internal wires broke. I just grabbed another USB cable, spliced it and then sleeved it with my own sleeving. Looks much better, is more flexible and much more durable then the original braiding. Unfortunately the USB cable I used wasn't very long and doesn't reach very far. So I purchased a G500 and a have my G5 as a backup. G500 hasnt had any of the issues.
Also for feet, I purchased some AMAZING mouse feet from http://www.slicksurf.com/
for my MX518. They are 100 times better than the stock ones that came on it. Super smooth like butter and a great way to extend the life of your mouse when the feet come off. I am still using my MX518 after 8 years of abuse and even replacing the LED in it from red to blue (just because).
Slicksurf looks like a pretty ghetto sketchy website, but it was fine when I purchased from them (using paypal). I would send them an email first to make sure the guy that runs it is still filling orders. I know for a little he had some family emergency and wasn't getting orders out.Edited by Imrac - 3/1/12 at 12:44am