CecilliaB, I never even thought about asking about his sire or siblings growth rate, but I'm emailing the stallions owner now, so I'll be sure to ask her and let you know. I do know that his sire was 15.3hh and his dam was 15.1hh.
As for everyone else, thanks for the critique and the compliments on Finn. I'm somewhat small statured, so if all he grows to is 14.2hh, I'm happy, I would just prefer if he grew to 15hh.
dirtroadangel, we actually did try the string test, and it didn't look very good haha. I'm hoping that it's just wrong because he was too old to try that test on :P