I, as Turks, had a great time beating the Byz not through brute force but through hit and run tactics. Go hire a bunch of Horse Archer Mercs or make some of your own. THe best thing about the better kinds of you can find them (Boyars) is that you can use them to crush units from behind if oyu can sandwich a tired unit towards the end of a battle. I don't mean invading with your army and using these in conjuction - but only sending the amount of HA's in which you can feasibly control and harrass the enemy before retreating. It's the only way I could go through teh Byz without losing too many men and it works very well - even against the Katatanks - just make sure you pick your targets well and it'll work amazingly well.

Good luck! Those Byz are some of the most formidable opponents all the way through the game, mainly due to their Heavily ARmoured and Elite/Jedi General troops.