My Saint’s are mega powerful. Truly effortless, one finger braking on a DH bike on proper DH tracks.
BUT…I’ve has loads of bother with them. They feel horrible. They pull to the bar then pump up and basically feel different every time you pull the lever which does not inspire confidence.
I thought it was a set up problem so I persevered with them for ages and then heard that loads of other people suffer from the same issues. Try them, but if you get a dud set send them straight back. I left it too late.
My SLX’s on my hardtail are perfect. No lack of power and total reliability. Never tried XT.