The time, money, and thought look like they're paying off!
It's an impressive build!
If you're having soft breaking, have you tried Salmon coloured pads? I'm not sure if they'd help or not. Some nice big mountain bike disc breaks seem like an obvious next step... not that you should listen to this armchair critic, necessarily.
I get the sense you're pretty proud of the no welds aspect of your build, which is cool. However I can't help but wonder if a frame builder could measure your build and translate it into a welded frame, or something. Who knows? It might save a few pounds. And given the absolute bada$$ery of your brainchild build, maybe they'd do some sort of discount?
You've also got me wondering if there isn't some kind of Wikipedia for cool home builds like yours. I feel like others considering hand cycles might dig some of your innovations!
I'm a fan!