On my 05 LS V6, I dogged the crap out of the engine from 22k, to 65k till it got totalled by a friend, and it ran like a friggin champ. I mean, it sounded good, quiet in the cabin and outside, really smooth shifting and all that.
On my 05 LS V8, I bought it wat 45k miles, and now im at 60k, and it sounds good and shifts a little more aggressive than the V6, but the only problem I see on it, is the suspension doesnt seem as comfortable as my V6.