Heli-coil questions

Never used these, (I have used Helicoils) but they sound like a good alternative. just an FYI:
TIME-SERT® is a thread renewal system Easily repair stripped or damaged threads

http://www.timesert.com/

I have also used NutSerts (http://www.imperialsupplies.com/grp270.shtml) they work good for some applications as well.