I realize that Noxxic has 2H edging out DW by about 10k dps.. but this is with BiS gear correct? I'm wondering if DW would be better for lower ilvl?
First mistake was going to Noxxic. Secondly, both are competitive, so play whichever you want to.
DW pulled ahead slightly in 5.1, 2H seems to be pulling ahead slightly in 5.2. It's mostly what spec you're best at playing.
I love my Dual Wielding. I finally got the reforging and gemming working for it and it's doing fine.
Use whichever you have the best weapons for.
This is the correct answer. While gearing up you have to take what you can get. If you get into raiding down the road you have the flexibility to go with whichever weapons are used less by your raid group, increasing your group's loot efficiency.
Make sure to read the frost stickies though, because 2h and dual wield have different rotations.
The biggest thing for which spec to play to keep in mind is weapons since frost and dks in general are extremely weapon dependent. Currently 2h is ahead slightly but it's not a complete blow out. you'll probably notice a bit but overall it's not too much of a difference to where it's game breaking. Go with what you're best with.
how do you change your dw / 2h specialization for frost
You don't really. You just equip a 2h or 2 1h weapons. Although, you do have to wait....30 seconds, I believe, or the talents for each, motfw for 2h and tot for dw, to come up.