OP here. Thought I’d report back since others have posted. Got the Helix Floor and have used it some, though not extensively.
My thoughts are that, if you can see well enough to read standard print, you should be able to use the screen (unless the dark background is a problem). This is not super comfortable, since you may need to get your face close to the screen, but doable. HX Edit is also usable if you can use other software visually, but you may need to play around with the computer’s color scheme because HX Edit uses a reverse color theme that may not work for you if you already use a reverse theme for the OS. Also, both in the unit and HX Edit, there are icons that may be difficult to see, but this seems like an inconvenience, not a deal breaker.
Regarding the scribble scripts, I like them because they may help me see the switches when playing, though I can’t read them. They also help in seeing what’s assigned to what when tweaking.
Finally, I was able to get up and running much faster by purchading a couple of third party presets, in my case from Worship Tutorials (no affiliation, commercial or spiritual). Now, bear in mind that I’m no tone purist who absolutely must tweak everything to express my unique creative essence — I jist want stuff that works. If that’s you, these presets make life much easier for newbies who don’t see too well.