I've thought about the 'slow' comment, and it is admittedly vague. I think I always thought of the Bryston as less refined sounding than some others. For example, many will disagree, but I find the Levinson to be uninteresting, musically. I am not sure if it lacks dynamic contrasting, but to me, (just to me IMHO) not interesting.
The Bryston, (and I was a dealer for them for a short time) many years ago; the same characteristic sound is found for me in their OEM Lexicon Amps. Solid well built, probably never break, but not as detailed as some others I like more. Hell, maybe it's just neutral.
Just, not a fan of it's 'sound' perhaps.