I would consider the next step up for re-usable fasteners - a
keyed insert. The brand name I know is Keensert. These are much more robust inserts, but do require some specialty tooling. I would see if a local machine shop would lend the tooling to you. This was our standard insert for aluminum vibration tooling to allow easy install of control accelerometers. We found that using tanged or tangless helicoils over and over again was a bad idea and once we switched to Keenserts the problem went away.
-matto-