you heard correctly; of the ocean view double with balcony staterooms catagories BA and BB on Caribe deck have the largest balconies.
Dolphin deck is almost entirely mini-suites which are almost 50 sq.ft. larger including balcony.
I've been on both decks and much prefer the mini-suites. You have a larger bathroom with tub, more closet and storage space, sitting area and a larger balcony.
The deciding factor for me is length of the cruise; for 7 days I'm quite comfortable in the Caribe deck oceanview with balcony; any longer than 7 days I go for the mini-suite.
Hope this helps.