I'm using a BPT 3.5 Signature to excellent effect.
It DOES NOT reduce dynamics in my system. It does provide a palpable, almost eerie depth and width to my soundstage compared with my old AC conditioning units.
AC conditioning is a very subjective topic, sometimes giving rise to well argued opinions that are in complete opposition to one another.
I suggest finding a manufacturer with a "money-back" trial period and putting some units through their paces. In this case especially, YMMV.