I'm not a fan of this yet either. I use Tekkit because Technic runs like shit on my computer and has a few mods I don't desire or have any interest in (Thaumcraft, Mo'creatures and a few others).
It didn't come with Optifine, not a problem, installed it myself. Copied my save across from Tekkit lite, click it, Minecraft crashes. I try again, "Server closed"
I think I'll just stick to the outdated Tekkit lite, at least that works for me.
Just read that I will indeed need a new world, fuck that, I've spent ages on this.
Back to lite I go :)