I pair a couple of EVM-12L Black labels (the 300W version) with a pair of Celestion G12K-100s, and I couldn't be happier with the setup!
These speakers handle anything you can throw at them (and I'm throwing high gain, chugging, (hopefully) articulate riffs at them. They do pair really well with the celestions, which have beautiful grindy tones. The EVMs are crisp and clear, never ever ever muddy. To my ears, they sound fairly 'flat' in that they reproduce all guitar frequencies fairly evenly. I don't mean this in a bad way, the sound is absolutely magnificent.
Whether they are worth the price tag is another matter. I'm glad I did it, and I don't have money to burn, so maybe that goes some way to answering that question!
I did a review a while back, I shall try to dig the link out.
Roo