No it isn't, I don't even have a mountain bike! And I haven't complained about anything, I've simply asked whether there is a noticeable difference between the two versions of the BB7.

To wb: Thanks, I was already aware of the stupid UCI cyclocross rules, but I don't find riding around in circles with a bunch of other people to be very interesting, so the rules don't matter to me. My cyclocross bike is my "go anywhere in any conditions" bike. The rim brakes on it work great in good conditions, equally as effective as disc brakes most of the time, but on the road in the rain or on muddy trails, braking power is greatly reduced. Since I'm slowly modifying this bike to handle everything that it possibly can, getting a disc brake on it is going to improve braking in certain situations.

There's no chance of "converting to STI in the future" - the bike came with dual STIs, and I immediately removed the left-hand one - I just hate using them for front derailleurs, bar-end or down-tube shifters work WAY better, and I'm very unlikely to change my mind about this (I have all 3 of my single bikes and a tandem set up this way: STI for the rear derailleur, bar-end or down-tube for the front derailleur).