Is there something equivalent to the new PRT Surface in SR?
Not yet.
Do you feel it would be useful in your KSR workflow?
The PRT Surface wasn’t necessarily added because Krakatoa needed it, but we have something else cooking that made it a good idea. I am sure you will discover it sooner than later 
Is this another feature like the Kong shading? 
PRT Surface does sound interesting for cases where PRT Volume isn’t faithful to the EXACT surface without having very tight sampling. And it potentially might be faster (though I haven’t checked). But considering that SR has PRT Volume and other mesh support, it just seemed like it would be easy to maintain feature parity with MX. We’re hoping to provide as much parity as we can for the sake of our artists, so they can easily transfer techniques back and forth, even if I don’t have a specific use case in mind now.
Playing around with in MX, and yes, do want. Looks like a really nice way to include matte objects in a render to double-check the positioning and intersections.