The problem is: this makes it almost impossible to use the CT fonts for body copy texts on websites. If you declare the fonts in a CSS like:
"calibri, Verdana, Arial, Helvetica, sans-serif"
you will have to choose the right type size for either the ones who have the CT fonts or the ones who doesn't. If you focus on the old Core Fonts, the CT fonts will be rendered much too small and if you focus on the CT fonts, users without it will see much too large type. So as a web designer you are really in a pickle here …
There were plans for a CSS attribute that would scale the fonts according to the x-height (font-size-adjust), but it has been dropped in the current CSS specifications.
Any ideas or solutions on this subject?