Welcome to FT and congratulations on your upcoming nuptials!
I was at this property about a month ago for 3 nights. Used SNA to get confirmed upgrade to beach front cottage. First night I was told there were no OTWBs available but I could have one on my second day. Packed up my stuff and went to my OTWB. My only experience with OTWBs was at LM Bora Bora and it was fantastic. The docks went a long way (perpendicular) from shore and the water under our bungalow was deep and full of fish that we could see through our glass floor.
In the Maldives the docks/bungalows run parallel to the shore, thus are all in shallow water. Plus there is no glass floor. OTWBs are much smaller than the cottages and the bathroom nowhere as spectacular.
After 10 mins of pondering, I asked if I could go back to my old room. Much preferred my beachfront cottage to the OTWBs. Now if it's your first time with OTWBs, you might like the novelty. Ideally I'd suggest splitting your stay to try out both room types. I loved the outdoor shower in the cottage. ^