Although I use a conventional alignment table with BB attachment I really suspect that having the head tube, seat tube and rear wheel on the same plane are all that really matters. I have mastered mitreing tubes with a chop saw and 20" disk grinder. I don't do it often but it's pretty liberating. Most of the frames I make are extremely complicated and elaborate set-ups are often required so that is where I find my challenge. It took me about four months to build 25 of these. *edit Having trouble with flickr and photo posting, my apologies*

http://www.flickr.com/photos/frankthewelder/4683157591/