@Superdoggy - It may have to do with the TTF generator that FontStruct uses. Years ago, I made a font that was 8 pixels tall. Then, I expanded it to 10 pixels tall for an outline version. Unfortunately, the resulting 10-pixel TTF was half (½) the size of the 8-pixel TTF (!).

No matter what I did -- raising glyphs up and down around the baseline, adding a "dummy" glyph that was taller, etc. -- I could NEVER get the TTFs to be the same size at the same Point value; I ALWAYS had to set the 10-pixel TTF at TWICE the Point Size as the 8-pixel TTF to get them to line up properly.

@Superdoggy - Sadly, no. I did tell Rob Meek about it at the time, but I don't know if he ever found the cause or problem as to why it was happening...