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Getting a second opinion is a good idea but I would say the only skimpy place is the 16 IOC. Maybe doubleing them up under the tub would be a good idea.
Our deck is WAY overbuilt but I'm happy it is......8x8 pilings topped with 3 2x12's topped with 2x10's on 8" centers under the tub and 16" centers under the rest of the deck. The decking is 2x6's. This baby doesn't move one iota. So I agree with tman.....8" centers under the tub adds a little cost but adds a lot of support.
Holy smokes DAWG, you build like me (or I build like you, or...whatever)I was wondering why that addition cost ya 50 large. Now I know... Drewski