As always, it depends on a variety of factors - including the recording. You can't get great performance out of a mediocre track. The only real fault I find with Grados, in doing classical, is the narrow soundstage. For rock music, there's something fun about being up front. For classical, I think the expectation is just the reverse. Lots of classical aficionados prefer to be further back - some 10 or 20 rows. For the high side of that, there's the HD800, but even a used K-701, at around $200, will give you a very pronounced spaciousness, one that classical heads seem to prefer.
But note for note, I can't fault the Grados, which get beat up by the bassheads for not being bassy enough for that club feel. The one area in which Grados get tagged as excessive in their bright presentation, one that favors mids and lower treble - which, oddly enough, is a lot more classical-friendly than their bassier counterparts. Grados present a lot of clarity, with an extra splash of presence between the high mids and lower treble, an area that actually favors acoustic instruments over the heavy siss of metal. On my Grados, I prefer tracks that offer more natural instruments. It's the artificial stuff that fatigues me and offers less clarity.
