Heli-coil inserts are fine, and as mentioned much stronger than the original material.
You also have the option to shorten them up for holes without sufficient depth to accept all the threads, or double them up for deeper holes for more threads.
I install them daily in our shop as we retore thousands of old carburetors, many will require heli-coils at one or more places due to the age of the material and thread errosion, etc.
Just a note on heli-coil installation in soft materials. In most cases it is NOT necessary to drill the material. If the threads are stripped out, pulled out, missing, etc, the existing hole is usually large enough to start the heli coil tap. It's pretty easy to "hog" out the hole when drilling them unless the base material is clamped down and a drill press is used.
Use PLENTY of lubricant when tapping the new hole. I use clean ATF here as it's just easier to obtain than cutting oil. Make sure the heli-coil insert is at least one half to one full thread below the surface, or it can bind up and split the base material.
For most chainsaw stuff, I tap/heli-coil to 10-32, as we stock black oxide coated fasterners in Fillister heads, and Pan heads in that size in lengths to 3". The 10-32's are also almost exactly the same as the metric screws used on most Husqvarna saws to retain the starter cover and many other items......Cliff