I guess the most overpowered thing on EE is the ability to "create" matter with the collectors/relays. I dont think the power items of EE that use fuel are that overpowered, as mining a 16x3x3 field with the DC costs you 1 glowstone dust in EMC, which is not that little.
If the collectors are removed, as well as every ability to create matter out of nothing, then I would consider it balanced. That includes combinations like the block breaker + condenser/eternal density or maceration of blaze rods + condensing new rods.
However I dont think the other stuff in EE is op, changing matter into other matter is very much the core of this mod and if matter is limited, than it should be fine.