So now I am using the M 50 1.7...
First, an ISO 800 test. I think the camera did well and ISO 800 is very usable. With the K20D I tended to avoid ISO 800 because I thought the noise was ugly. This noise, I don't mind, especially since it does seem to keep a lot of detail. I took other ISO 800 pictures just for observing this (detail) but this is one that mainly shows how it affects the bokeh.
I usually tend to stick with ISO 100-400, with 640 being my indoors low light max. So I think I'll do just fine with this in low light.
Now on to a couple with ISO 100. The colors of the K10D seem to work better if you don't underexpose, at least that's what I'm finding out for now. With CCDs I tend to underexpose just a bit and add fill light later to get better colors, but I don't need to do this with the CCD. But that might be an issue because underexposing also allowed me to keep more highlights.
One more for fun.
I took some more but I need to be selective. What I did notice is that colors seem more true to life with the CCD. I'll keep taking pics and learning