@ emmny: Rude--they're 2nd-rate at best!!
I said it wasn't a 1:1, which is part of why it worked for me. Additionally, if they also didn't ~borrow~ aesthetics and general atmosphere on top of melodies, I definitely wouldn't care about them as much or at all (see also: Vajra). This isn't just in regard to Grieva--I like Gossip and DEZERT's attempt at it as well, though the latter isn't as blatant. In some bizarre way, it also helped me appreciate the originals more. I don't hate Diru (in regards to the era in question), but I also don't think you're only allowed to like one.
Give them some credit for sticking to their guns though: for as many people that love them, there's just as many who vehemently despise them quite vocally as well.
Just out of curiosity, do you feel the same way about other bands who pretty much the same thing? Grieva is essentially the vkei equivalent of A*Teens.