Rolled the dice here for one night during a last minute trip right before the holidays (which is trough season in Bora Bora). As a Gold, no upgrade was discussed before or during check in (wasn't even recognised as a gold), and I didn't bother to call in advance (wasn't willing to pay as already did OWV at Conrad Maldives). Despite 18+ OWVs and the Horizon Villas being available, I ended up with a King Garden Villa, which was still a great room (large and beautifully designed) -- but I think those coming here for their first OWV experience and getting "stuck" with these might be disappointed.
I was originally going to spend 3 nights here but after 1 night decided to save the points as I found the Conrad Maldives and Conrad Koh Samui to be significantly better all around. Following this one night stay, I went to the IC Le Moana for two nights, and as a Platinum member, both nights were upgraded to an OWV without asking (Thalasso didn't have last minute availability, but I did take the boat there for a day, which I recommend for the views -- particularly at sunset -- which are significantly better than anything at the Conrad).
In summary, if you're gambling for a free OWV upgrade in Bora Bora, the Conrad may not be the best choice (perhaps better odds if you're a Diamond), though the IC Le Moana was fairly reliable.
Having now been to the Conrads in Bora Bora, Maldives, and Koh Samui, I'd say I'd be most likely to return to the the Conrad Maldives, followed by the Conrad Koh Samui, and wouldn't return to the Conrad Bora Bora. In the Maldives, the OWVs are more private, have better views, and all have plunge pools + if you're stuck with a "base" room there, the beach villas in the Maldives are far superior to the "land" rooms in Bora Bora. Secondly, the breakfast spread in the Maldives was significantly better than in Bora Bora. With the Conrad Bora Bora, while the hard product is modern and nice, the resort is otherwise quite small and boring, and doesn't have the iconic "Bora Bora" views. That said, if you do go, I recommend going up to the Spa for sunset views, which were very nice!