Do threaded on suppressors (directly to the barrel threads) have much of a POI shift? I am assuming they are less than ones that utilize a mount.
Yes, no and IMO it doesnt matter. If you are buying a suppressor for a carbine, I highly doubt you will ever notice the POI shift. POI shift depends on the suppressor, the barrel, and the ammo. No matter what suppressor you choose, there will be a POI shift. Again - will you notice it? From what I have seen with several suppressors a POI shift of 2" at 100yds is extreme - a fighting carbine may shift under 1" at 50yds - does that really matter?
If I go with a threaded on suppressor, how easy are they to take on and off?
loctite it in place, and use a strap wrench if necessary to remove it. Piece of cake, no big deal.
Will taking it on and off damage it or cause unwanted wear and tear?
not if you do it properly
If I go with a threaded on suppressor, and I remove it from the gun (AR-type), should I expect anything bad other than a lot of noise?
nope, just dont expect to see anythign after your first shot fired in the dark.
In other words, is shooting a rifle with no muzzle device a bad idea??
If you are going to be practical, the thread and leave it on is the way to go. I had to rethink my M4-02 on my SBR after the first day of a carbine class. Why was I stuck holding onto an extra pound, when no one else had suppressors and I need hearing protection? I shot the second day of the class with a Gemtech G5 removed half the time.
Also, I’ll opt for detachable for the cool factor - this is just a hobby to me.
Define what you need and buy what you want. If you have more than one carbine, its easy to buy more than one quick mount, but is the extra cost of the QD worth it?