Imo science and engineer should be merged but it would take a tremedious about of effort to do so, giving hazard emitters to a eng would make a lot of science biased escorts underpowered (esp against the borg), that is assuming that Emergency Power to Sheilds (or whatever) would still require boff slots on those ships, I partly agree with Emergency Power to x being ship based but it would cause a lot of issues (such as do I use Emergency Power to shields 1 and 2 and use a universal ensign for science or do I use Emergency Power to Shields 1x2 and RSP (so in short lack of customisability)).
maybe same as abilities like BFI, that all captains get, APA should be something all captains get as they level. that would basically solve the problem of sci captains not being able to damage as well with 'THIER' sci skills, and make any eng shooting weapons less pointless. would just have to think up something else unique for a tac captain then. all the captain types should be at least partially geared for dealing damage, no mater what kind of captain they are they still carry a gun, and fly around is heavily armed starships. and the only thing you need in the PVE is damage, yet 2 out of 3 suck at it. the typical for mmo tank, dps, and control types is such a stupid thing to apply to a game about star trek, with no magic and starships made out of metal.
Giving more offensive BO abilities to TAc BOs would only increase the escorts online phenomenon.
Sci and Eng need offensive choice, otherwise i don't see how APO as the resits all, lovely defense buff gets to stay in the Tac department. (same thing could be said for APD). The original design seems to have intended for all Cmdr. Slots to have offensive and defensive choices. I think that we should stick with this design. Hybrid BO layout would sufffer greatly, if we go with your proposal in my view.
The problem is the lack luster performanice of things like AB (to much CD), sci resists, and the poor performance of single beams, and the beam boosting eng powers. Fix these and there ll be a place for all beam sci healer (eng/sci)
As ddis points out, tac/sci is poorly balanced compared to sci/sci. fix sci boost and resists and we have viable sci/sci build that do things in pve and pvp.
nerf escort defense via tacteam and apo and we suddenly have all classes and ships back in game.