I hit tier 2 in beta and had both a cruiser and an escort. I really liked the cruiser because I like using phasers with their wide firing arc. But I lovvvvvvvvvvvvvvvved the escorts maneuverability and how fast they could drop kling ships in pvp. Plus watching youtube videos of the defiant in action kinda makes me wanna go escort.
Would an escort ship with an engineering officer have at least decent survivability?
Not really. They're faster and more maneuverable because you're supposed to get in and out quickly, not take hits.