Hey Calclavia, I've seen what you're doing all over the forums. I would suggest steering away from the name :"add-on". I'm not saying that it's my personal opinion, but it suggests a "lesser" mod, which would probably turn away potential makers.
Speaking of UE, I think it's a great idea. Personally, I'd like Physicraft [my (extremely) WIP mod] to implement it in the near future. The link is below, and i work on it every day. v0.3 will have a lot of new features, so son't fear about the current noobishness of the mod. Eventually, i want to tackle some of the stuff ic2 adds (dusts and such).
http://www.minecraftforum.net/topic/1278793-125-wip-smp-physicraft-indev-v02-moar-industrial-stuff-download-available/