So, some friends & I were having a discussion about ems vs. pts vs. % for web fonts (yeah, we are dorky like that...)
Pts are a print unit of measure. Ems are relative to the parent element and scale which is good for mobile and user experience (e.g., I can scale it how I want). Of course, some times you don't want scaleable, but most of the time you would. I personally like % as it forces a certain amount of consistency of display (it is based upon 12pt but is scaleable). So, yes on % or ems
...but don't use pt unless you want to lockdown display.
Two great resources:
pts vs ems vs %
and a conversion chart.