I'd expect it to work about as well as Ido, the better-than-Esperanto: not well. The whole point of currency (and language) is exchange. As you limit yourself to ever-smaller numbers of people in the search for more ideal manners of exchange, the missed point becomes harder and harder to ignore.
I might try to learn Ido someday. I probably won't talk to anyone in it, but it might be fun. It has one advantage over Esperanto: its vocabulary wasn't chosen by one guy arbitrarily, but by a committee that analyzed various European languages and tried to find common word roots. That way knowing Ido might help me to dig some meaning from French, Spanish, Italian texts.
I think Interlingua would be even more interesting to you then, since it was designed to be comprehensible to ordinary speakers of French, Spanish and Italian without any special knowledge. It's sort of like a modern idealized Romance language. It would probably serve your purpose better than Ido.