Thank you, so the upgrade should help.
High-dpi support has received another set of improvements, including support for non integer scale factors commonly used on Windows.
I created a test build with a new Qt version to check if it really helps:
https://www.dropbox.com/s/haqzu8rwx6wifcb/vstudio_x64_10_win.exe?dl=0
I downloaded this version and it somewhat better, not completely yet. I am including two screenshots. One at 225% screen increase size and the other one at 250% screen increase size as a recommended setting by Windows. This should help you gauge your work on your side.