I have my default font set to Leelawadee UI, FYI, but I've run the test on Arial and Times New Roman.
About 2-3 months ago after one of the updates, I noted all my notes in 10 point being much larger. I tried a few things but didn't spend much time on it. Then today I tried again, using 12, 11, 10, 9, in three different fonts. I didn't see a difference between 11 and 10. I believe 10 is 11, they are the same, and 10 should be smaller.
Using 6.10 SR-2 (6.10.0.0041) on Windows 8.1