I played up to a T3 Science in beta but I've canceled my game order now. I was planning on going Escort though. Mostly because the game in it's current form is more zerg pew pew DPS chart than it is tank/"heal." I use the term "heal" loosely because it really doesn't exist outside of a shield transfer that will pause a death for 6 seconds or a hull repair that's only real use is to repair a tank faster once the combat is over. As a general rule once your shields are gone you're dead. So I don't see a real need for hull repair outside of maybe PvP. That's the only time I've seen hull repair actually become useful and only then because of the threat of stealth attacks. NPCs don't offer that kind of problem.
I'm going to split my ship use: Cruiser and Science Vessel. I played the Cru through the Klingon Scout Force Fleet Action and used BO powers to heal the other players. That was cool. Transfer Shield Strength is great in groups! But since I solo most of the time I switched to Emergency Power to Weapons II.
My Cruiser is named after Sir Earnest Shackleton's ship during his failed expedition to Antarctica in 1912-1914. All the men survived, though the ship itself was crushed by the ice. An amazing story! My T3 HC will be the USS Shackleton.
Science unless I just can't keep up in fleet actions while leveling. It probably shouldn't be a problem, I got top 3 many times in a mostly stock miranda due to slightly paying attention to what I'm doing. I'll use an escort if its the only way till level cap, then back to sci for fleet stuff with my fleet.