You really only get 2 class-specific skills per rank -- 1 space and 1 ground. For example, the rank 1 Tactical space skill is Attack Pattern Alpha.
Other than that, at least as far as space is concerned, Tacticals, Engineers and Scientists are identical. (For GROUND combat there are big differences but for space, a Tactical and an Engineer will only differ by 1 skill per rank.)
So, tactical officer in a cruiser? Sure, why not.
The argument could be made that you should maximize your abilities, though. Attack Pattern Alpha gives you a damage buff, so the more damage you have TO buff, the more helpful it will be. With that in mind, you'd want to be in the highest DPS ship there is: an Escort.
Similarly, Engineers get Rotate Shield Frequencies, so you'd think it would make sense for them to be in the ship that gets the biggest shield bonus, which is Cruisers.
But if you tend to like hybrids, then a Tactical in a Cruiser would be giving up some DPS for some survivability. He'll still DPS better than an engineer in a Cruiser, but he won't tank quite as well.