I asked this question specifically at the recent IA meeting. The ASI said basically what TJ surmised. That the Avionics guys were the only ones getting involved with these. His understanding was that a radio, for example, has the same requirements whether it is installed in a Jetstream or a Citation (oops, let's say a Super Cub or a Husky). Any detailed supporting documentation (like indicating head combos that are shown to be compatible) that is so obviously the same as to not matter WHICH airplane you installed it in would be sufficient for the approval being applied for. He supposed, "let's say you had a field approval to put an automotive voltage regulator on a Pacer, you could use it for a follow-on for a Super Cub." But he also said mechanically (as opposed to electrically), he didn't see any differance or advantage from going the regular route, because there is no "ultimate differance" in how you get -or don't get- an approval. Basically, its "Much ado about Nothing", not an easy way around.