That's a sweet bike.
the falling into 2nd on the grip shift is a problem but I just put a bonus spring to pull the arm back and it's solved
often with the gripshift too I find the problem is the shift selector on the grip. I had that problem and seen others with the same, where it gets worn so either it won't pull all the way to 1st, or if you adjust it so it does, it wont drop down to 2nd well.
hand cramps yep.
there used to be stronger springs you could get. seem to be unavailable anymore. ebay.de from the same guys that made the uber clutches, but they were only like 35E for the stiff springs.
I like the oil slosher idea too. but I dunno that it helped
I actually just got my old 2 speed back, which is insane - fuck the swoops - but I'm curious to dig in there and see what I can do, having thought about it some more.
I unfortunately let go of the uber parts on a different build, and it's just a "stock" D, been dicked around with a fair bit by the folks who'd owned it and passed it around since I let it go til the swoops got it back; but man - great bike.