Actually more like the "Engineering Major"
Acetylene is not necessarily better than Propane. In fact the by products of each reaction are identical in that CO2 and H20 are produced. It's just that propane has a much larger envelope when welding, which although awesome for lug brazing is more difficult for me to use when fillet brazing or doing very small work.
The acetylene flame can be adjusted to different types of work and for that reason it is more useful overall. You have to weigh the safety factors (propane is safer) vs costs etc, but the reason Acetylene is so prevalent is that it is useful for all sorts of welding/brazing and cutting where propane is really only great on general heating and brazing. For fillets acetylene really is the preferred fuel and since you have it already it seems like a no brainer.
As far as the utility thing. Not buying it

I/you could have brazed your commuter together with one dollar of bronze and saved even more money. The use of lugs costs a lot and for that reason alone deserves more respect than just covering it with any ol thing. You could have in fact bought a new mass produced frame for 100 dollars thus saving yourself more dough. Building your own frames as a hobby makes no actual financial sense so IMHO it should be done right, the craft deserves that much at least.