After a little bit of testing, I've found that these monitors do accept a signal from the Indivision, but only in 1.25 mode, so all games will look like jerky shit through it unless you switch to Composite mode, which does seem to work fine from the Amiga's internal composite output.
When using one of the S-Video adapters from AmigaManiac (the V1.0 model) there is a stutter in the screen, making it jump a little bit every five seconds or so. This happens with both S-Video and Composite from this adapter, but there is no jump from the Amiga's composite output.
So it's not completely useless, it's just far from ideal.
When outputting 1024x768 into this monitor, it shows all 768 lines without stretching or interpolation, but horiztonally it still interpolates the display, even in 4:3 mode. It's barely noticable to most people, but to a pixel artist it's unacceptable. Why this monitor can't display a true 1x1 pixel-for-pixel 1024x768 mode is beyond me, you'd think they'd at least make it accept this resolution natively, but it still thinks it needs to blur it a little.
My CD32 is buggered so I'm not sure if I'll be able to test the S-Video output through that on here, but I have a feeling I won't see the stuttering that we saw with the RGB-S-Video adaper.
I really hope there's a way around this, maybe the new V2.0 adapers will work better with monitors like this.