I just had one litereally blow up last night, thank god it was in a bucke of water, I had it for 3 months, I got it december 26th 2001. It was a rio 1100. I bought two rio 1100's and one maxi jet 600. The maxi is silent, ,and I mean silent, The only way I can tell it's on is by looking for floating stuff to get zipped along by the current. both rios I had were fairly quiet for about 2 months, then they were loud. one died yesterday, Thankfully I was able to return it for an instore credit. I shelled out an extra 23 dollars and replacecd it with a maxijet 1200. so now I have a maxi 600 and a maxi 1200, and one rio 1100 I will be replacing the last 1100 very soon(as soon as money can afford, likely not til the end of the month though).
Something to keep in mind about rio's the warentee is only 120 days, compared to a full year with the maxi's.
I would go for a maxi.
Read my post for the details on how it blew up.