we've had a red riverx 1k for about 3 or 4 years. it's a step up from the old yellow tahiti model but the quality is still on the ify side. my kids used it before they got adapt at hardshells and now it's used by their friends when we go on a river trip. it's been down deso a couple of times, westwater a couple, the san juan, the platte, golden and all in all it's held up pretty good. it certainly hasn't been babied. we've had one valve problem, a small pinhole leak which has been a pain to keep repaired and one side of it went flat in westwater for an unexplained reason.
i don't think it's as stable as other 1k's...but of course it costs mucho less. the kids did surf it in joe hutch on deso though and i was pretty impressed.
truthfully, i'd spend a little more and get a higher quality boat. over the years i've been most impressed with aire and hyside. the new, less expensive nrs boats may be pretty good too.