It doesn't seem like there are hoards of people out there complaining that their rotafixed cog slipped, even though many people on this forum will tell you that its dangerous. I've seen way more threads about people with stripped hubs, loose lockrings etc. As far as I can tell the rotafixing method is pretty safe and a good cheap way to start out riding fixed. Please relate your successful and unsuccessful rotafixing experiences and if rotafix failure put you in a dangerous situation. It would be nice to come up with a even a vague idea of failure rate.
Me...2000 miles with 42/15, skipping and skidding for at least 1500 of those miles, no lockring, no locktite, and no slippage to report.