Well mate, the reality is - a genuine full CF bonnet will cost anywhere between $1,500 - $2,500. I don't know about you, but I can't justify spending that much for an original full CF bonnet, say, ordered directly from Nismo or Top Secret Motorsports etc from Japan. All the CF bonnets you see floating around in Austalia are mostly copies with around, say, 60% CF on top and the bottom is mainly fibreglass - if you go for the even cheaper ones that's around $400-$600, the top is really glossy-looking so it's not even true CF anyway - and yes, all this is more for looks.
Most CF Bonnet copies come from China or other surrouding Asian countries. If it's slightly performance you're after, then go a CF bonnet copy, if it's true performance that you're after and can afford it, I would go full CF - whereas it's just the look you want, you can always get a FG one and see if you can get it painted cheap.
I'm in the same situation as you - can't decide what to do... and I really can't afford a full FC one to be honest...but all the copies that I've seen just don't cut it as they all look so shonky... also, have you seen what a chipped FC Bonnet and a damaged windscreen looks like? I have - a mate of mind has one on his S14, going at highspeeds and the thing flipped up and smashed his windscreen - both look like an earthquake's hit them... I might even stay stock... don't know yet.
Let me know how you go...