Hi.
I agree with some people : shotgun is a very good weapon, who is usefull again a lot of alien classes, with building, but poor at distance and useless againt rants if you are not a good dodger.
I usually see good players taking shotgun vs s3 aliens, and killing them (even if they are good). It's not like a chaingun + bs, but it is at a lower cost.
Oh, and if the shotgun is really the only usefull weapon in Tremulous, what's for the others?
Lasgun is very powerfull, with no reload, good at distance and close combat, but with goons, you have to be a good dodger. With Mass driver, if you are a good dodger / you are at great distance, it can be a good weapon. :-)
Each weapon at his own utility, and focus on only one weapon don't make you a good player, just a shotty guy who doesn't want to discover the others weapons. It's like the people who always dretch -> goon -> tyrant.