I made the microwave bowl potholders for Christmas and myself. I've had mine in the MW for 4-5 min. And no problems. Potatoes are generally in there longer so maybe that's where the problem lies? I personally just wash, poke holes and then zap my potatoes in the MW. And after i heard that you don't have to wrap foil around the potatoes before they go in a regular oven, I was real happy about that too. Just a pain! LOL
I think a convection oven is hotter than a MW oven. I don't think i would use the potatoe bags in there. Isn't it like a regular oven with a fan circulating the heat so it cooks faster?
Walmart.com has wrap n Zap for $3.09 per pkg. FYI