Well, the extra Tac ability slot is nice, for sure. Tac Team 1 + two whatevers instead of just 1 Tac ability in addition to the Tactical Team.
Of course, you could throw EPtW1 into the Ensign Eng slot on the Negh'var, so it's not like it's exactly apples & oranges. There are ways to make the Negh'var do more damage.
For my purposes, I probably should have gone Negh'var first, then purchase the Vor'cha later. Lacking non-c-store appearance options kind of sucks since I don't have any of the other Vor'cha choices... nor do I really intend to get them. Since I'm used to the tanking role from other MMOGs, I could have used the heavier boat for that edge in tanking.
Of course, the extra bit of turn lets me actually put torpedos into play (currently using Photon Mk XI for the extra bit of reload speed vs. Quantums, and will go with Rapid Fire Transphasics eventually). I even have aft torpedos because it's Klingon-y, but I am considering swapping it out for another Beam Array. If it were the Negh'var, I'm not sure I would use torpedos at all.