I've covered the G27/T500 a few times, but here is the thread where I started my T500 mods:
T500 Install. The first post covers it.
I have a second HR rig at our race shop in southern Ontario. It has a "black retail box" (latest generation) G27 on it and I like it every time I use it. The flavour of FFB is quite different, but after about 1/2 an hour I'm pretty close to my hoe rig times. And after a couple of days on it I'm always faster. Then coming home I find the adaptation is not as long, but getting the ultimate time is longer ( as in a TT for example).
Also, the FFB feels quite different. I have to alter a tune to get the car to feel the same between rigs using GT6. That wasn't something I expected! But they are different beasts. If the G27 had a slightly stronger FFB and a better durability, I would go back to it straight away, but with a smaller wheel (no bigger than 300mm).
Hope that helps. Ask anything more you can think of.