I just recently was in the exact same position as the OP. . .I've read thread upon thread, upon thread, upon. . .wait where was I. . .oh right. . .that raved about Grado and their performance for Rock and Metal. I will say they they did not sound horrible, and I will even venture to say they sounded "good", but I was ultimately let down. I found the DT990's, K601's, HD600's, and even my pair of SRH840's to sound better for those genre's.
The pair of Grado's I picked up were the SR225i's as well, and if I were coming from something along the lines of a $20-$40 headphone I could see the Grado's sounding very good to me, but when compared to other headphones in their price range, I am honestly left thinking to myself "What" while staring blankly at the small piece of plastic resting on the desk. I gave them a full month's tour of duty and ultimately sent them back. I feel the resell value of a headphone is a way to see their true value in the community, and Grado's (at least the SR225i's) are about like driving a new car off the lot. . .the value plummets instantly (at least from my findings in checking the FS forum here).
Ultimately I would say to pick a pair up if you are curious, as we all have different ears and different likes/dislikes, so the true sense of these cans will obviously vary. But between the build quality, the feel in my hands, the feel on my head, and the sonic qualities of these headphones leave me questioning their price tag. The sound they present might be more upfront, yes that is
fairly true, but all fullness to the sound is completely lost. They produce a sound, which I feel was best described in my friend's words as, "small, the sound is just small." Which in my opinion is hard to do considering how "upfront" and "in your face" they are touted to be.
. . .just my 2 cents here. . .feel free to hate me
Just as a reference, my two favorite cans are the HD600's and K601's.