hmmm, so I was wondering, given that I tend to use the smallest four on my PG-990 11-34 and I've got double & bash guard up front how likely is it that swapping over to a road cassette would make my calfs & lungs explode and render me sobbing upon my rear tyre as children on scooters over take me on the slightest of hill?

or would it give me more POWAAAH and WEHEYHEYHEY along with the obvious GNAR x RAD to the power of SICK that having a road cassette on a mountain bike affords?

I dunno, I reckon [to an extent] you just adapt to what you have

There's a climb I do regularly on both a mtb & a road bike, I end up with both of them in the lowest gear I have – 32/32 & 39/25 respectively

it seems equally as hard on either, not a direct comparison I accept but ………

I have been riding with a road cassette for quite a while now as i am a bit like you(only using a few at the back).Also if you choose wisely and work out what ratios you need you can pick up a good cheap and light cassette.I have just bought a Specialities 9 speed cassette second hand for £12.50 delivered and it only weighs 118g. 😯 A good cost effective way of saving a few grams. 😉

Got double & bash Saint cranks, and a 12-27 road cassette on my Chamelion, nee probs!

hmmm sounds like a plan then 🙂