I use them as does most of my dnb mates ... Give them a ring or email and speak to paul.... nice guy. Most of the top dnb people use them.. mampi swift, GLR .... etc. You can even go to their studio with your music.
i wouldnt recommend using differnet masterers though, stick to one, build a relationship, makes it a lot easier to ask for a discount lol,... thing i like about audio animals is they will give you some advice on your track before mastering, they do mixdowns too
I think it's a bit subjective–while the type of gear used by the mastering engineer is crucial, what's plays more of a critical role (in my opinion) is how knowledgeable said engineer is with the gear he has at his disposal. Instead of thinking the extra cost goes towards the equipment, think of it as going towards the skills of the engineer.
As I said before (and as its been repeated), Subvert is outstanding, though I'm a bit bias because we've used them for all of tracks and therefore, they've gotten to know the "sound" that we're looking for with the finished product.