I'll third that. An Ambassador class would complete the Enterprise progression.
I just wish that the Ambassador class would come with a bridge pack of its own, looking similar like the Enterprise-C bridge but with more modern looking displays( and maybe an option to choose the more retro look also).
And I believe the Excelsior-class does not have her own bridge yet either.
Speaking of the special Jem'Hadar BOFF..it is a pity that one cannot even customize the look or even change him to a SF uniform. Takes a lot of value away from it IMHO, since the guy would look very much out of place. So I personally decided not to include one to my crew, at this time anyway.
In officer exchange programs in Science Fiction, it's not at all unusual for the officer to retain the uniform of his home fleet. A Trek example would be when Riker served on a Klingon ship. So it's perfectly natural for your Jem'Hadar officer to be in his own uniform.