I don't think you have anything there that would benefit from 16GB or RAM.
As for the rest of it, personally can't say there is anything beyond what I've already mentioned.
I'm in the Intel camp right now. I like the much higher IPC and lower power usage. However I do have to AMD systems in my house. My daughter has a FX4100 (she doesn't need much power) and my younger son has an older system (AMD Phenom II 955). For me the performance systems are all Intel.
And back to the graphics card.
Other than that, it seems like a well rounded system. Good choice not to cheap out on power. XFX is made by Seasonic who are a very respectable name in power supplies. I've recommended the Hyper 212 EVO many times here and I have two systems in my house with them. It's hands down one of the best coolers for the price.
Though I don't have personal experience with AsRock, I've certainly read some less than shining stuff about them. Particularly cheap PCB's. From what I've read, their PCB's are quite thin compared to other manufacturers and bend quite easily. This sort of thing worries me. I'm a EET (Electronics Engineering Technologist) and when I read about that type of corner cutting, it makes me wonder. I'm an ASUS fan. Used to be a GigaByte fan, but I got burned once and I've never been back. Never used anything from MSI, though I've read many good reviews.
As for your purchase date, if this is being bought close to Christmas, you may not have much option with the 770. These aren't being made anymore, and once discounted, they won't be in the retail channel long. You are talking over 2 months away, so I wouldn't count on them being available then.