I returned and all went fine! It rained some days, some other we had a splendid sun (XMas day has been great and we had a BCD beer party in the middle of the channel.. lol). We haven't affected by Usman at all.
Probably December isn't the best month to do if you look for every sun day, but it didn't effected the dives at all and the visibility was OK except in a couple of places.
It was my first time in the Philippines, people are really friendly and helpful, it has been probably the most relaxing scuba holiday I've ever had: I don't remember to have ever moved a tank or even transported my fins myself (lol).
Scuba wise (talking exclusively about December as I dunno about the other month) I still prefer the Caribbean area as fishes, visibility, reefs type; but in PG the difference was about the diversity (I never seen that much different "things", mostly small toh, together in the same place...) and the people, whenever it was about a specific Operator, ppl really made a huge difference coz it was like diving with a big family and friends (even if you knew these chaps a day before).