except that you cannot guarantee that what you see will be what your viewer sees at 100% text size - so you will still need to check that out

don't mean to be unhelpful

presumably you have got round this problem too:
I suppose I could go up to 125% DPI, which would mean 80% becomes 1:1 pixel ratio... BUT all the Windows applications (including XARA dialogue boxes, I may say) start to misbehave....
well done