Fusion reactors like in GT5 unofficial (recipes and tiers), fed with EU or LU or QU and you need to upgrade all the blocks (e.g. control computer mk1 -> mk2 -> mk3), The same with casing, coils, and other blocks.
As GT is a realistic mod, make 1.9. compat system (more realistic)
It all depends on whether a combat system is something that should be included in GregTech, and if that is the case what other things should be included.
Personally Gregtech to me has always been about realistic tech progession but I did jokingly state once that I look forward to the day when GregTech became a be all end all mod.
At the end of the day it all depends on what Greg wants it to be. Things like combat systems, well you could always have another mod do that.