Are you considering any brands other than hope? I know they have their fans and they're certainly well made but i've never been that impressed with any hopes i've used.
Don't get too caught up in 4 or 6 pot, I have formula megas on my cannondale, they're 2 pot and are hugely powerful, even in the alps. Same goes for formula The Ones, which are often considered amongst the most powerful out there.
If I had £200 to spend on a set of brakes it would go on formulas (megas or the ones, check their website for clearance deals). You'd also get saints for that budget. Failing that I got a set of avid code 5s off here for I think £85 posted. Even they are plenty powerful for anything short of full on dh racing.
Any brand other than Hayes , also i like hope as they are easy to bleed.
I almost had a set of Formula the one for £200.00 but they sold.
Thanks for the info , i would prefer mineral oil to be honest with you.
And was looking at the Older saint, or newer XT.
I think the most powerfull brakes i have used are the old XT 4 pot.