People talk as if you HAD to use lava to power everything, if you think something is OP just use other things to get your BC power.
And people love to talk about how solars give free ad infinite energy, yet they forget how easy an automatic tree farm is, infinite charcoal and saplings (Biogas) for your BC engines.
I'm talking about SMP and how it creates problems on servers. FTB is a pack for servers afterall, not just for single player. What you do in your single player world is up to you. But if you pump lava from the Nether it's affecting anyone on that server, unlike a forestry setup (unless you spew craptons of entities into the world but that's another matter).
I'm not saying infinte renewable energy is a problem. You need it, especially on servers. But in in my opinion solars and lava are too easy and too 'fire and forget'. Don't forget that for a forestry farm you still need to create humus. It's possible to fully automate it but it's not completely trivial, unlike creating solars is. Sure, solars cost a lot of resources but that's not an issue with quarries and stuff. The point is that it's easy to set up a system that, once created, keep generating free energy forever. If you don't agree that's an issue, fine, but that is my opinion.
I don't think it's the biggest problem (if you remove gregtech especially) but it certainly does show some bias. He mentioned in the IC2 forums that he likes to use lava energy and I think it may just be an unconscious preference that does indeed seem to make this issue more prevalent. Either way it does go the other way from his goal of balance, in my eyes.
If he just wants to build neat stuff that he thinks is just cool, fine with me. But if he completely disregards the balance implications of the stuff he creates he should not be in the default modpack (the one we're all still waiting on, *sighs*).