Catapults on the whole aren't that hard to kill. Aim center mast and you can't help but hit their heads with half of your shots.
The trick is maintaining composure when you take the first alpha and try and ignore the brown stain in your pants.
IMO though, the Splatcats are such a PITA because they can:
1) Carry Jump Jets (that work now)
2) Run a max sized engine (almost 90 km/h), so don't say "run away from them" because unless you're in a light or very fast medium, you can't.
3) Torso twist to fire damn near behind themselves (almost 180 degrees).
This means that they can (usually) outrun you, outmaneuver you, escape you if they start taking more damage then they'd like, and shoot you if you do manage to get behind them.
They're one of those 'Mechs that die quickly and spectacularly from 400m out, but bring death and destruction from 100m, and are almost impossible to shake for anything under 40 tons.
Edited by BDU Havoc, 11 February 2013 - 06:44 AM.