love the vRS alcantara seats, but their bulk eats up rear legroom -  are the cloth ones in the vRS significantly slimmer ?

I think you would regret downgrading to the cloth seats, even with the benefit of additional space (if this is the case). The alcantara do lift the interior and are nicer to sit in - a close family member has a vRS with cloth and I have alcantara so have some basis for an opinion 👍

I have cloth - I've seen people being derogatory about the cloth... I don't understand why.  I appreciate the Alcantara may be better but I find the cloth seats to be great.