of course there useful,they get u out of the sh1t!the least things u have to swap over to ur second gun the better.
I have 3 guns,Eclipse Cocker (main gun) then either my Imp or my RT (was my main gun for 2/3yrs).
Even a cheaper basic gun can be a life saver to u or ur team cos if ur mates gun goes down & he dosent have a back up u can let him borrow urs so ur team aint a man down/gun down for a game/day.
I have let people (mainly the Pimps) borrow my guns may times before even my beloved Cocker!
If u can get a second gun even a spyder on co2 do it coz ud thank me for saying it!