I encountered the same Problem as Loc: The count returned by bbp_get_user_reply_count does not update with the user’s activities in the forums. The bbp_get_user_reply_count_raw computes the count directly from the database, which is computationally more expensive, but  delivers a correct count. 
Furthermore Robkk is right: I just had a look at the source code of bbPress 2.6-alpha, and has added and hooked some functions to correctly increase and decrease the post count on user’s actions such as creating and deleting posts.