so far from my experience i managed to beat the banshee...
i had a halucination build which i used that allow me to hit their ramp pretty quick and fast (halucinated VR for scouting and drawing some fire lol)...
even when his banshee is out, u got time b4 his cloak finishes so snipe that banshee ASAP, micro ur stalker towards the techlab/ starport...
once that is down u are pretty much homerun...