Switching up play styles is a bit weird but only takes a few hours to get sue to it and build up muscle memory and proc watching and what not.
DW is better for most of the cleave fights and add AoE bits.
It all depends on what weapons you can get your hands on and whether you have the tier bonuses yet. I've got 489 2H or 476 1H so 2H wins out for me atm.
I'm playing Frost 2H (474 ilvl) and have got top 50 rankings on pretty much every parse - cwatididthar? Parses don't necessarily mean it's better as good RNG will probably have more impact on your dps than weapon choice.
In terms of sub 35% phases the DW rotation is definitely a lot easier to manage than 2H.
I'm very glad that both specs are very close so it gives people some flexibility.