Without Recurrent Complex you will find this pack a lot grindier. Because the structures RC generates contain some nice loot and allow some short cuts to be taken.
I'm hesitant to say you will "really" need it, because people are very resourceful and come up with all sorts of ways to overcome almost insurmountable problems.
But I made extensive use of glowstone, netherrack, lava and of course all the dimlets from RC structures, which were the only sources of these items in my first dimension.
I think you would really struggle without access to these resources and I would recommend working a bit harder to resolve the problem before giving up on that mod.
KeepOnDigging!