It definitely voids the warranty. Perhaps I'll hold off and keep my eye out for any steals on a Dragon that may present themselves. If our Monarchs arrive soon I guess 30GH/s won't make much of a difference anyway.
If BTC ever goes to $10,000 then 30 GH/s at the current difficulty will still be worth something nice.
I've discussed this at some length with a fellow Fan and we lean towards opposite sides of the fence.. Me being a little too ready to accept the risk, him possibly being a little too cautious.
Perhaps if you find a deal on a Dragon, maybe we could consider doing 1 and monitoring it for a week or so - see how much difference in temp there is, etc. Then revisit the issue once we have that knowledge?