I agree with aje, my motto is, if it ain't broken, don't fix it, call me crazy but if I'd send my headphones for repair, I wouldn't want them to replace my drivers, even if the swap is made by Grado themselves. The reason is that i have bought all of my Grados because i liked the way they sound as they are, need I say more?.
Some of you may already know this, but Joseph Grado himself is offering an overhaul for his famous HP1000, at around $1300, if not more, it's far from what I consider afordable, so, needless to say that as much respect as I have for him, they're is no way I'm sending Joe my precious HP1000. First, as I stated above, i like the way they sound as they are, second, i find the cost, prohibitive, third, they might get dammage, or lost in the mail, and fourth, Joe is an elderly person, and works at it own pace, so for some it has taken months to get their headphones back. Finally, and I really don't like to think about this, and I hope that he's going to be with us for many more years, he is 90 so, anything can happend.
Regarding ferday's post, I'm sorry to hear that you can't easily demo Grados because I also live in Canada, and I have access to any Grado model I want. To answer your SR80i upgrade question, think that the SR225i, and the RS1i, would be my two suggestions at different price points as an upgrade to the 80i. I know that you like the SR80i's sound signature, I do too,, I think that they're great headphones, especially at their low price, but if you have the chance, try to demo the PS500 or the GS/PS1000, you might end up preferring one of them's sound signature, I know I do.