I've had a degree of success knowing that size. As long as I'm rendering for devices I have on hand, it's close enough to be close enough. Examples at:
http://home.comcast.net/~brewt.blacklist/site/
And I've tried cascading the font calls, which also has a degree of working, if I uninstall the first font, the second one seems to kick in (at least, in ade).
I'm finding that whatever sense I had when designing the set of numbers I'm using now is weird enough that I'm having trouble porting it to other font sets.
Hence, stress, consternation, frustration, desire for mansions.
-bjc