The big ring on my 11 speed cassette is slipping with a new chain. I see the new Shimano 11 speed cassette is cheaper than the SRAM version. Can I use this new Shimano cassette with my existing X01 drivetrain?

You can but you need to budget in a new freehub body as Sram uses the XD freehub body and Shimano use the conventional ones. This is what I’ve done.