I don't know about the Sniper Rifle. I think sniping bites anyway ><
I'm more of a "Sweeper Team" kinda guy.
allow me to enlighten you in my Space-strategy.
Start by picking the pilot(Timebombs), get to a gunship of your faction. take off, fly to your enemies' hangar without getting your a$$ blown off. Land, get out, start wasting the troopers inside and make your way towards the Shield Generator. Drop as many Timebombs as possible, and fight your way to an ammunition droid to reload when your out of bombs. If the generator hasn't blown up yet, return to do so.
this will give your comrades outside the chance to blow out the ships candles(so to speak). since you're inside the ship anyway, continue to destroy the Auto-Defense Turret CPU(should take care of those big cannons shooting your ships to bits.) reload your bombs, and make your way to the Engine room, where you blow up the engines using 3 well placed bombs(with well-placed I mean nothing short of the bomb being IN the tubes). reload again and blow up the ships Life Support systems, just for the fun of it. After all this is done, all internal systems should be blown up, and you can make your way into the Hangar again. once there, pick a Fighter/Bomber of your preferation, take off, and finish up your bombing run, taking out the ships outside organs such as Communications, sensors, and the Targetting Bridge. If you haven't one by this time, try taking out the Frigates, if your teammates haven't done so already (probably not, the A.I. doesn't realise the frigates are taken down faster than the capital ship, plus it gives an advantage of not having to look out for them so you don't fly into the things.)
This strategy of course can be interrupted at any time by a hostile soldier blowing your brains out, meaning you have to start over.