I don't think GT adds any more complexity than what already exists. Before it we still went into NEI, then drilled down through the various components needed, built the extended machines needed for said components etc, etc. I remember the first time I went to create a forestry farm, needed carpenter, then fabricator, then had to make engines, fuel for those engines, then pipes, then humus. Then I had to power up those new machines with even more engines, to make more components to make a simple tree farm. I don't see that as any more complex than what GT adds. The only difference is that there are blocks in GT that simply take time and no amount of crafting or smart wiring or pipeing makes them any faster. But even then, as etho showed in the first server rendition, even the time aspect can be overcome with enough of the same block. As for balancing, you might want to also include mystcraft in with those mods "Not for a server", as a All time Day world with enough solar panels can spit out UUM like it's nothing, but then they'd just move to the nether. I can't agree with any kind of balance argument if more than one mod is being considered at any one time. Like Azanor says there's no way for him to balance it for all the mods out there, so he balances to vanilla, and if you're playing vanilla MC, EE lines up nicely.
@Golrith, nah we'd just set up systems to auto craft replacements, and store them near what they're to replace, some kind of indicator, and boom, you wouldn't even notice them wearing down.