Why not?
I prefer Grado's, they have better bass than Sennheisers and just the same range, I don't like ear encompassing/enclosing headphones and find the Grado's more comfortable. Also they are cheaper
Go into a decent music shop and try before you buy though and make up your own mind.
If you do decide on Grado's you may aswell stick to the SR60's, had mine for 7 years and all I've had to replace are the ear cushions. My dad has got the HD595's and loves the extra treble for listening to his classical music.
I agree that the Grado SR60s sound great but they're the very last cans I'd recommend for gaming. They're just plain uncomfortable to use. I had a pair of SR80s but got rid of them after a couple of weeks because neither my son or I could bear to wear them for more than a short time as they were so uncomfortable.
Have you seen the number of recommended mods for the ear pads of these cans on audiophile forums?
FWIW I bought a set of Sennheiser HD 600 which suit me very well and are probably overkill acoustically for games. Based on my own experience I'd say anything but Grados for gaming.