It doesn't matter what its called, if it reduces muzzle flash then BATF will call it a flash suppressor. I believe that's what DSA is going through right now.
Also, the Post Ban barrel cannot have standard threads on it unless they are covered permanently by either an approved muzzle brake of some sort of thread protector/sleeve.
Then if the A2 style compensator happens to allow the attachment of a grenade launcher, that also is illegal.
The only way you're going to get anything from BATF is to write them a letter explaining you're point and they will either agree or disagree. Calling them on the phone doesn't work because it seems the people that answer the phone hardly know what they are talking about. I had a question about muzzle brakes and when I called I had someone answer the phone and argue with me, telling me I was wrong without hearing the whole story. He just kept quoting me the section about flash suppressors in the AW Ban. I decided to write a letter and although it took many months I was in fact rewarded with a letter of agreement.
About getting unwanted attention, I wouldn't worry about it unless your question went something like "I've been making Full Auto Weapons and selling them to school children for over a year now and suddenly I hear this might be illegal, is this true?"
Good Luck
I just wanted to add, if you decide to write then here's the address:
[b]ATF Firearms Technology Branch
650 Massachusetts Avenue, N.W., Room 6450
Washington, DC 20226[/b]