I dont guess I ever really noticed that there was much difference in how a ROM looked vs. how a rigid front looked on a tractor....The ROM might make a tractor sit just a tad higher in the front than a rigid, but I cant really think of any other visual. It would be hard to tell the difference from a galloping horse :)
I do know there is a ton of difference in how they ride and drive across uneven terrain with a ROM vs. a rigid front.
As for whether or not they A and G are the same... I wouldnt take anyones word for it but rather, I would consult the parts catalogs which are both viewable and downloadable from JDPARTS by clicking on "parts catalog" on the homepage.
Good luck with whatever you decide to do but I'd plow with it a round or two before I took it off. Who knows? It may win you over to being a ROM lover :)