Hi Jen
We're going to Disney in 3 weeks and we decided to buy Sara her seat. Not only do I think it is safer, I think the trip will be easier bc she's used to her car seat. I think she'd be to squirmmy (spelling?) on our laps!
Good Luck & have fun on your trip!
p.s. I'm so sorry to hear about your FET! I know how disappointing it is, when we did our 2 FET's, our embies didn't even survive the thaw! Good Luck & give your precious Mason a big hug & kiss!