I registered just to post this, so I'm gonna toss in my two cents.
Lava Reef is my favourite song from any Sonic game, period. I have every remix of it I can find, good or bad.
Personally my favourite so far has been Jivemaster's remix of it, but this one is a really close second. I'm not a professional musician and I haven't sung since All State Madrigals many years ago, so take my opinions with a grain of salt.
First, I think this remix really portrays the feeling - I can only assume as I wasn't there - of the night that these remixers had together. I don't think it's kind or that this is the place to deaden this expression by picking fights with them.
Secondly, I really enjoyed it; but it could be because Pixie's style of vocals is something I've been trained in since I was younger, though not as extensively as she.
My final verdict is that I love this song and its expression. I'll be looking for more awesome collab-work from you guys in the future!