Im gonna have to agree with chetchat on both of the issues here. Regarding moving out of state and leaving the weapons behind....remember how all of this tax stamp stuff started. I has to do with interstate commerce, that is the only way they could possibly get all of this unconstitutional BS to fly. Don't you think that the BATF would like to know where every single NFA weapon is at all times? Of course they would, so why don't you legally have to tell them when ever you move in state? Because by law they can't force you to tell them. As long as the guns stay in the particular state they are registered in then they are untouchable by the feds.
Also, its clear that only FFLs give up any sort of privacy rights to the BATF and even then it is only at their business premises, not thier homes. Even what can be done at the business is limited, meaning the BATF can't just decide to do a surprise inspection on you at your business once a week for an entire year. Even though they don't always play by them, they have rules too.
One more thing Robert....This sentence caught my attention and Im not really sure what it means.
"We've been leaving Class III just as you described at a Class III dealer when going on long vacation or business. "
If this means that weapons registered to someone else are being left at the local dealers place for safe keeping until the owner returns, then unless they are completely unaccessable to the dealer himself, BATF would consider this an illegal transfer. It makes no difference whether the dealer is an SOT or not, he still may no possess NFA items that are not registered to him, unless they are being repaired and a form5 was opted not to be filed. Maybe Im off base here, but that is just how I read it.