I've used engineering and Tac in escorts. I think the primary choice in which ship to use is not what class you are but you're playing style. I find escorts good for driving straight at an enemy, taking the lead out and then pushing as much damage as possible to the survivors. Cruisers, on the other hand..tend to wade right into the middle, delivering broadsides left and right and generally mocking enemy fire for the confetti it is.
I've preferred escorts, but occasionally got the urge just to warp into SB2 with a cruiser just to laugh at the poor little birds of prey as they failed to dent my shields deeply enough
As an Engineering Officer, I found escorts to be moderately survivable. Mostly because my innate powers made up for the lack of a second engineer Bridge Officer. Between me and the ONE engineer on board (with a lot of changing of power settings in the mdidle of battle) we managed to keep the ship in one piece while doing monstrous damage to enemies.
I had to spec specifically for the weapons I was using, and I had two Tactical Bridge Officers that I groomed JUST for the escort, but it was a mean little ship.
Ultimately, do whatever works for your playstyle, that was just my experience.