When I ordered my CoMo Speedster in 2004, I had it spec'd with a rear Avid disc, but also had V-brake and Arai Drum brake bosses put on as well. I have all the bosses/cable guides necessary to run both a V-brake and drum or disk. If I do ever run rear V-brakes though - I would only do it with a drum.
Instead of not getting the steel fork with the Wound Up CF upgrade - I got both - so I could have the steel fork with mounts for panniers. Front disc brakes were not an option at the time so it have V-brakes. If I had the choice though - I'd have discs front and rear - but at this point the cost to upgrade to a new WoundUp Fork and disc compatible front wheel isn't worth it to me.