I also have gotten all my rebates, probably 50-60 in the past two years alone. But then, I take some precautions:
-- send all by certified mail, so there's no question about whether or not the rebate was received on time
-- make copies (scans) of everything
-- double-check that I'm compliant with every little detail
-- follow-up on pending rebates and call if the rebate is late.
On the whole, rebates have been painless--I've only had to call on one rebate and the problem was fixed immediately.
Of course, this all takes some time, so I don't go through this routine for small rebates of $10-15.
BTW, here's a review of the Ultra 600 watt by Jonny Guru:
Biggest problems appear to be low efficiency and fan noise (duh!). I'm tempted to get one and replace both fans. At this price, why care about voiding the warranty?