The OP’s M530 should be nearly identical to the XT in terms of platform/contact points, no? Would the DX provide more actual support? Struggling with the floaty feel of SPDs myself, albeit with “cageless” M520’s, but I’m also worried that M530/XT Trail won’t make much difference.
All the “trail” (530, XT, XTR) type pedals are very similar in size and shape. The main benefits, to me, are the ease of clipping back in and some impact protection.
The body in the DX is set very low in the cage, so there is more sole support from the pedal. With deep tread shoes, Mavic Alpine, I can’t fully clip in without putting a plate spacer under the cleat. They work well with a flatter sole, I use Tevas.