Great Inventions . . .

The HeliCoil, invented by a smart German in the aeronautics industry, allowed the use of lightweight components (aluminum) to be used in engines.  The ability to meet torque specifications in aluminum with a corrosive resistant thread (stainless).  HeliCoils get a bad reputation because installers don't follow directions.

1. Use the proper drill size and tap

2. Always break off the drive tang

3. Finish with the new HeliCoil just below the surface

4. Use Loc-Tite (as recommended)

5. Never remove fastener when engine is hot (ie: spark plugs,

timing plugs, engine covers, etc . . . )

6. Readily available

HeliCoils are an effective (and very cost effective) fix to stripped threads.  Yes, there are many other products that you can argue are equal or better, IF installed correctly.  Most other inserts require a hole so large, that if it ever comes out - you are really screwed . . . (pun intended)
If I met this German in a hall, I'd buy him Weihenstephaner.