There are a fair number of SSH's in the Mo-Kan area and I've never heard of anyone who didn't love them. Nothing but good to say about them - although in every breed there's probably a rotten apple or few to watch out for. By getting him young, and doing your own ground work, you can increase the odds of him growing up with a good work ethic and good manners.
I am not good with colors but would just add that as far as dapples go, don't underestimate the lovely dapples that can come with good nutrition. My B&W tobiano TWH mare has dapples...
As far as registry, check out the hardship registry rules for the SSH registry. You might have some luck with one TWH parent's papers. Also, there is another registry for pleasure/trail horses that are gaited. It's based on whatever parentage you know about, and a video proving that the animal is gaited - here's the link. http://www.pshr.com/
Have fun with him - he's beautiful!