Light pre-pass really doesn't give you anything at all in the way of material variety, at least if you're going with physically-based lighting approaches. All of the interesting variety comes from things that you need as input to the lighting pass, so the whole "minimal G-Buffer" thing doesn't really pan out.

Yes you're right, my choice of words wasn't all that great. Light pre-pass doesn't solve the material problem, but will give you somewhat more flexibility, but as you said it won't give you the flexibility you require when it comes to input.

And about OP's experience level, since he seems to be quite keen on building this advanced engine I assume he'll have to deal with quite advanced techniques from the start, so why not inform him about the available options. Whether he'll be able to actually pull it off (the GI technique, or the engine in itself) is another matter, and will be something he'll have to deal with himself.

@L. Spiro:
Thanks for the great links, I'll be having a more in-depth look at these later today (my engine's lighting pipeline could always be a bit better)