Once you use a timesert, you'll realize just how crappy helicoils are. I used to run a foreign-car-only machine shop, and that's all we ever used. After getting used to them, and then having nothing but a helicoil (after I quit), I swear I'll never use anything else. However, if your hole is already tapped for helicoil, you may be commited to helicoil, or welding, like you said.