Actually, wasn't the amiga hardware scrolling capable of "sub pixel" scroll precision by using high-res (or super high-res on later hardware) pixel timing with a low-res bitmap? Or did I just dream that one time when not very well?
You might have been dreaming, I don't know. Were you asleep at the time?
I can imagine that it might work for horizontal scrolling, I'm no expert on the coding there though, but Lo/Hi/SuperHi-res screens all have the same number of lines... (Lacing excepted, of course, but that just doubles them all, so again they're the same).
