I fly a Galaxy-X, and honestly it's better than the R, although there is little difference between the two. Really the only difference is the consoles, and the Ens Boff slot. (On the Gal-R its an ENG, on the Gal-X its a Tac)
One thing I have found really interesting after looking at the Ambassador, is the Ambassador and Excelsior are RA level ships. The Galaxy-X and Galaxy-R are both VA level ships, but aside from the Galaxy's having 1000 crew compared to 700 and 750, they are virtually the same. The Galaxy X/R, and the Assault Cruiser Refit need a boost to put them more in line with the Oddy Command Cruiser, and less closely related to the RA level ships.