Thanks for your comments. After reading them I sent off an email to the TA that booked my trip and asked her for her opinion as well. Gave her the "you're the expert so that's why I'm asking you" line and hopefully she'll be honest with me and tell me what she really thinks.
Not 10 minutes later I got an email back from my TA and here's what she said:
"If you are going to use your balcony alot - definitely change for the larger cabin. I think you would love it."
She didn't say a word about charging extra. I think I'm going to get her to change it to the Caribe. I KNOW we'll be using that balcony and I could care less about the privacy thing - not like we're going to be doing anything private out there anyway, even if we could!
Sure hope I'm doing the right thing.......