Rivnut is just a brand name (what's the code for trademark anyway
) for the generic threaded insert.
There's a fair amount of strength difference between designs, especially resistance to turning and pullout. If you are going to use a 1/4" thread, the cheapo installation kits are marginal and the bolt/nut method above may be your best bet - especially if you're going to use a steel insert. Steel would be my preference for anything beyond 10 lbs per insert, or something that will removed and replaced more than once.
You can get a good idea of the selection from the
McMaster Carr catalog (search on "nut insert").