This topic comes up a lot on motorcycle forums, and there is usually someone who will tell you that you're courting disaster if ride on a plugged tire. I don't know where this idea comes from. Do people really think that a steel belted radial tire is going to catastrophically fail and fly apart because it's been plugged? Worst case scenario is that the plug leaks, and you end up with a flat tire again. In a lot of the poorer parts of the world where they can't afford to buy a brand new tire every time they get a nail in it, I'd guess there are a lot of plugged tires rolling around with no issues.
I never plugged a tire with one of the mushroom plugs, but I've heard other guys complain that they didn't work as well as a string plug.
2014 Yamaha Super Tenere
2012 Suzuki DL650 (traded)
2004 HD Road King Custom (sold)
2000 Yamaha Road Star 1600 (traded)
1994 Yamaha Virago 1100 (traded)
1982 Honda V45 Sabre (traded)
1984 Kawasaki 440LTD (sold)