Yeah, I think UHJK might really make the most sense.
j still moves you in the same direction as ctrl-j (linefeed)
h still moves you in the same direction as ctrl-h (backspace)
there's never been a good association between k or l and their ctrled equivalents; no gain or loss there
u is now up - mnemonic ftw
moving undo to ctrl-u would make redo (ctrl-r) more discoverable