Great review Ben. Goes along with the one I did in Tape-Op, only yours is better.
This REQ2.2 is the only EQ that got me to sell my beloved Pultecs... no EQ would ever get me to sell my Pultecs... but this one did.
Tim built this EQ with real chokes and filters... most EQ's just simulate these (on a chip). It took Tim 10 years to get it right... but I'd say he GOT IT RIGHT.
As for the softened low end... no more than what a Pultec does... and I owned both tube and solid state Pultecs. I'd say the Buzz matches what the solid state low end sounded like (which were tighter than the tube ones).
That said with tight Q's I use the low end of the Buzz all the time. YMMV.