Hello,
I know I'm not one of the guys you've been talking to, but I gotta put in my own two cents on this one. Stick welding (SMAW) is far from obsolete, and is in fact the only way a great number of welds can be made. The book you are using probably refers to stick as being obsolete in the area of production because GMAW (MIG welding) is more productive and more efficient. If I am in the shop, I am using either a TIG or a MIG, the former by choice, the latter by force. It's boring and requires less skill (please nobody hammer me on this one, I just never was impressed with it, despite its advantages). I've even turned down jobs because I would only be using a MIG. As for O/A, yes, it is an older method, but it does work, and a couple of bottles are far less expensive in the short run than buying a TIG unit. Everything has its own applications, for example, I have repaired numerous cast iron pumps and parts with O/A brazing, something that TIG wouldn't work as well for.
All that said, in your situation, building custom bikes, MIG and TIG are going to be the two processes that you will want to learn. They are quick, efficient, and clean. Stick and flux core are fairly "dirty" and are more for thicker steels than what you use on a bike. O/A will do it fairly cleanly, but you will log a lot of man-hours into a bike because of it. And as for the "little girls" that can weld on monster garage, most of the female welders I have met could have easily welded circles around me, so don't think its just "that" easy (women have naturally steady hands, something I have destroyed with Copenhagen).
Anyway, good luck in your learning,
G. L.
G. L. has said it as well as anyone can. Now- you have the interest, go- take that course, you have nothing to lose but a rather small amount of money. Even if it turns out that this is not for you that knowledge itself is a positive since it releases you to go on to something else.
Bill