I think that, if the Federation met with the Galactic Empire, they would steal and copy each other's tech. I have been a fan of both, and I say that the odd of winning are about equal. ISD shields are weaker, and have less firepower, but are larger in numbers and can overwhelm with quantity. The Federation, with powerful phasers and sheilds, would be able to damage more, but can be destroyed by starfighters in large numbers. But, by at least 3 years of combat, they would copy each other's tech and tactics.
Turbolaser + Phaser= Turbophaser. I would love to get my hands on that.