I was interested in trying a port of
Edge Grinder as a little diversion a while back - that uses the CRTC R3 trick on the Amstrad CPC to get that lovely scrolling. But after figuring that it'd almost certainly have to be Master only (because of the sheer amount of graphics), I reckoned it was probably just better to use shadow RAM for the 1 pixel offset buffer, and get some double buffering while I was about it. But then it didn't seem like such a tough challenge, and I lost interest
I don't really think the R3 hack is particularly practical unfortunately. And it can lead to weird display sync issues if you try to change it in the middle of a frame too. Edge Grinder does that, but that's why there's a 2 character row blank area between the scrolling window and the status - to give the VDU some time to resync. You can't rely on the shift to be exactly half a character either - at worst, if you try to swap between a one pixel offset version of the status display on alternate frames using vertical rupture, you can get a horrible subtle vibrating effect where the two frames don't
quite match.
For horizontal scrolling, I figured you need big enough character sprites that a 2 pixel scroll doesn't seem so 'fast', or else you need to go down to 25Hz. It honestly doesn't look that bad as long as it's rock solid and you have enough going on to distract you from the scrolling judder. I tend to find that just focusing your eyes on the main character alone is normally enough to detract from the frame rate.