i have 31"x10.50"R15 on at the moment. heavy as all chit, and affected the response big time. i can fit 32"s and have minimal rubbing on compression at the front. like you said, u need to use a BFH!
i haven't had much to do with the taller and narrower tyres, my only experience is when my dad had a hilux about 10 years ago, and had some super grippers with 16" steel split rims.
would be interesting, to me, to see how they go and look on a vitara.
i watched a whole heap of the malaysian rainforest challenges, and they use pretty much a tall and narrow tyre on a 16 inch rim. i think anyway, one thing that got me was that, even though some had very low tyre pressure, hardly any of them ran beadlocks. is this the case for the skinny tyres? no beadlocks?
i dont really know what/where you drive, but i'm assuming that its a bit of everything. should it matter what choice you make, what do you have in mind craig?
in conclusion, i dont have much to tell you, in that most of you already know what i said, but if i could, i wouldn't mind trying to fit some 33x10.5R15 on a vit, and you did say you dont mind getting the grinder out.
the dude at
http://www.k9rdj.co.uk/ runs 35x10.5 simex ETs.
really, i have NFI!