Can it be removed on 14.5 and replaced with another perm. attached FH like a Phantom?

Yes.  Any decent smith should be able to swap them out.  If you don't have one near you, then send the barrel to Randall at AR15Barrels.com or Steve at ADCO.

Thanks.

A good while back there was a thread on that subject here. Back sometime around the end of the AWB. If I remember correctly, it's "blind pinned and welded", as in they screwed the brake on, then drilled into the bottom of it (and the bottom of the barrel a little), put a small pin in there, then welded over the pin, cleaned it up and parked the whole thing so that it's pretty hard to see where the pin is on some of them. It should be on the bottom though. If you want to do it yourself, just start filing/dremmeling the area until you can see the pin, then grind a couple of slots... one on each side of the pin, which will give you room to put some needle nose pliers on the pin and pull it out. Then just unscrew the brake, replace it with whatever hider you like and do the same thing they did to mount it permanently. Or, if I remember correctly, some people just put silver solder on the threads and then put the hider on and heated it with a torch to melt the solder and "permanently attach" the hider.