Omegas have never dropped at a good rate from cantina nodes, if I've gotten 3 omegas from cantina nodes in the last year I'd be incredibly suprised. Best source for omegas is doing your dailies and the omega events that show up a few times a week. Also get in a guild that's winning TW and getting lots of stars in TB and…
I start farming Veteran Smuggler Han Solo in cantina last week and until today I did not get a single omega ability. Thats 0% drop, somethimes i use crystals for energy, so i spend lot of energy to get nothing. Anyone have same problems.
Beside the Cantina battles there are enougth and better places to farm omega, imho. GW, ability challenge, ship ability challenge, daily activity, omega battles and you can buy Omegas in the ship store.