I really like the SR60's...especially for the $$. Interestingly, when I went to buy my Grado's, I was fully prepared to buy the 325's if they sounded the best. But to my ears, I liked the SR lineup in 'reverse order'...60's most, 325's least. The 60's seemed to have the most balanced sound signature to my ears.
Regardless, there's just something unique about Grado's sound. I really like drums and guitars (acoustic especially) on them. Listening to small jazz bands, folk, blues, some rock...they really are a treat!
My initial buying experience with the SR lineup made me hesitate to spend more for their 'better' models. That said, it's been years since I bought them and they still get regular playing time.
I should probably find a store and listen to their more expensive cans. If I could find a more refined Grado that had a similar sound signature to the 60's, I just might pull the trigger.