I looked at yesterday's post count compared today and PianoTell is definitely more active, but it's a short time frame that was sampled. I'll take look again next month.
Yesterday at 2:30 pm PST
Pianoworld Post Count = 3,362,331
PianoTell Post Count = 10,219
Today at 9:00 am PST
Pianoworld Post Count = 3,362,384 +53
Pianotell Post Count = 10,465 +246