I use both on the street and the track. I think that not using it at all, but leaving it there is probably and bad idea. If you don't use it, there is no point in the extra weight other than having a backup to the front system. Which is very unlikely to ever fail if kept in working order.
My reasoning for using both is that if I am more aware and comfortable with using the rear, if I know where it's limits are then I am better off. If I am in a panic situation, and have rarely used the thing it will be very easy to panic and lock it up. If I am not familiar with how the bike responds to it, and I don't have that subconscious reaction already ingrained, I'll do exactly the wrong thing. Do you really want your first experience with locking up the rear to be while you are in a panic stop situation? But if you use it regularly, and know how the bike will respond, then you will do the correct thing without even thinking about it.
The other highly beneficial reasons to use the rear brake are the fact that it is weak, placed in the rear and is better for any off track or offroad "excursions". With it being weak and placed in the rear, I like to use it better to *slightly* scrub off speed during a corner, usually the exit if needed, or to stop an unintentional wheelie. It is easier to make these small adjustments than using the throttle or front brake. Depending in what kind of surface you wind up on while going off track, the rear brake will help more than the front. I've seen quite a few guys go off the track straight up and down in an easily recoverable situation, grab the front brake and do an instant faceplant.
Just my thoughts on the matter.
Last edited by b.miller123; 01-15-2012 at 02:17 PM.