There were many people here advising getting a low-end regulator.
As long as you get one from a major manufacturer, it will work great, will be reliable, and won't stop you from doing any diving that you want to do.
Will it be as comfortable as the pricier ones? No.
So, if you think you won't miss that extra bit of comfort later, then go with an affordable model. If you think you may want something better later, then get it now instead of buying twice. (Regulators last a LOOONG time.) The Z2 will be as comfortable and high performance as any high end model out there.
As for Atomics, a swivel is the same thing, it may or may not be slightly more comfortable. The good news here is that you can add it later even if you don't get it at the outset.
Warranty for Atomic is for manufacturing defects. No free service kits etc. So Leisurepro will work fine. I would recommend buying from a local shop since a relationship with one will make things easier for you in general, but if you will be moving soon, I guess it won't make a difference.
The Atomic has a metal air barrel, which isn't all that common these days, many are plastic. However the body is plastic. I think the only major modern regulator brand that has metal second stage cases is Mares. But whatever you may have heard, I find it not much of an advantage. I'd rather have a lighter second stage.