You do lose out on the big tactical buffs, as well as weapon slots and turn rate. Those are big downsides. On the upside, you can use Gravity Well III (will need a sci captain to train it for you). Does quite nice damage and holds things in place for a bit. With the Lt Commander engineering slot, you can pick up DEM II, which should provide a nice DPS boost on your energy weapons. And you get target subsystem Is for free.

Sci does give you good survival powers, with TSS and HE. That can be further boosted by a couple of low level engineering ones, like EPtS and APtSIF.

So, just off the top of my head, something like this:
LT Tac: B:FaW or T:HY; APB I or else another offensive power of choice.
LTC Engineering: EPtShields I; APtSIF I; DEM II
Com Sci: HE I; TSS II; TSS III, PSW, or maybe Photonic Officer; GW III
Ens Sci: TB I, HE I, or TSS I
Lt Universal: another tactical, for more of the same.

Weapon focus would be mainly on beam weapons, although you could go for turrets, C:RF Is as the LT spots for the tacticals. Possibly a single torpedo launcher in the back. Could also go for something more focused on the frontal arc, say 2-3 DBBs, 0-1 single beam arrays up front, with 3 turrets in the back and rely on gravity well, target engines, and TB to help keep the enemy where you want it.