Helicoil in Spark Plug Hole

Does anyone have any experiences with Helicoils installed in cylinder head spark plug holes?

Reliability Issues ...
Safety Issues ...
Quality Issues ...

Thanks

well i ahe had to remove a sparkplug with a helicoil in the hole in my shop class you just have to be careful removing the sparkplug after you have installed the helicoil (for replacing sparkplugs and such) and you cant torque the sparkplug as much as you use too i had to torque the sparkplugs on the car to 15 (i think) they only to ten on the helicoiled one (dont use these numbers on our car)

just remember the helicoils are only stainless steel so they can strip really easily if you torque they plug too much