BuddyPress.org

What are you going to use the extra usermeta for? If you just need an easy way to store and retrieve some data about individual users, then using BP xprofile fields is really the easiest way to go – they can be created in the Dashboard, and all the registration markup & save/retrieve functions are all built in. If, on the other hand, you’ve already built a bunch of custom functions to query across usermeta, then it’s probably best to keep what you’ve got (saving in wp_usermeta) and hook some functions into the BP registration process.