I am on BES and everything seems fine. My battery lasts longer than 4.7 and 188.8.131.52, but I wouldn't call it amazing.
What really eats battery ever since I got the Tour is phone. A long phone call will just eat the battery up bad. No or short calls the battery will last a couple days easy.
Z10 and PlayBook <- 9650<- 9630 <- 8330 <- 8130 <- 8830 <- 8703e <- 7130e <- 7250