Are you contemplating having the brake installed now before chambering?
If thats the case I would advise against, best to have it all done at the same time. Normal operation is to chamber then do muzzle work so you know your barrel length. Not as huge of a deal on long barrels, but if you say were doing a 20" barrel and had the muzzle work done first, you would have to use an extension so the barrel was long enough to reach the outboard spider for chambering, which isnt ideal.
If youre just looking for opinions on the brake itself, the FTE are definitely effective. IMO, I think its a tad overkill for a 6.5x47, an APA Little Bastard would be sufficient and look way cleaner. Or any style brake you like for that matter that can be contoured to the barrel profile.