Ya, people may do it just to be able to try out those items. I'm not sure if that's a good or a bad thing.
I think it's a good idea, although I have a lot of good ideas from my original Foundations mod project that I'm restraining myself from including, to keep Proportions mainly about proportions, rather than about re-doing the tech tree and adding new stuff. But ya it's a good idea, as long as the crossovers are not overly powerful.
PvK