Yeah, I'm not a modal guy in the end. I've tried several times to use various modal modes in emacs (including evil-mode, emulating vi), which seem like they should be a good idea, but I can't seem to train my brain to work that way. The closest I've come is using god-mode in emacs, but I very rarely actually turn it on. I'm often joked that vi indeed has two modes: (1) beeping furiously and (2) break everything --- which turns out to be rather apt in for my twiddler modal experiment....
But, still, the num modifier is difficult for me to hold, so I've been trying it as a sticky key. This indeed makes the Arrow keys, pageup, pagedown, &c. into single button keys. It worked fairly well, though I kept forgetting which 'mode' I was in. Until I hit the twiddler equivalent of "break everything".... In addition to using movement via a 'sticky num', I've also been using the more traditional 'space' for scroll down and 'shift-space' for scroll up. Unfortunately, my inability to keep track of which 'mode' I was in, means that I ended up turning on 'sticky num', and then pressing 'Shift-Space', which of course resulted in the hard-coded Twiddler 'revert to default config' being executed.
I think I've given up on Sticky 'num'....