don't do it...they overcharge & may randomly decide they don't want to take your boards at the check in counter. i've never flown w/ them, but have heard all kinds of horror stories. one guy i know got slammed for close to $400 one way...almost as much as his ticket price.
delta & continental are 2 carriers that i will never fly due to their board policies.
going to central america, you'd prob. be better off w/ the taca group, a bunch of central american airlines that are actually pretty reasonable as far as board go. i've flown w/ them a bunch of times & never paid more than $150 both ways. AA isn't a bad option either, tho more expensive.
Delta charges $200 per board each way. You may want to check to see if a rental is available.
I did fly to Liberia, CR, over the summer on Delta and took an old board. I ate the two hundred bucks so as to not have to deal with going into Tamarindo for a rental (probably $125 per week). I got off the plane, went to the hotel and surfed playa langosta. I gave the board to a fella i met who snapped his the last day i was there.