Herman has a good point. Spending $1500 to save a few ounces in your luggage is a little questionable. (But, to each his own..) If you're looking to save weight, look for lighter luggage; you save pounds of weight for much less money.
There's another issue, if you're diving nitrox these are probably the worst regs to buy. Although it's highly unlikely that you'd ever have an actual issue, the facts that the Ti is not O2 friendly and both manufacturers have at one point placed restrictions on nitrox use for the Ti regs is enough to scare some dive ops. I could easily see a dive boat refusing to give you a nitrox tank thinking that your reg is going to blow up the boat.
Another questionable issue is that neither of these regs are ideal for cold water. You could get a MK17/G250V (or try the new A700 if you want some bling) and you'll have a reg that designed specifically to deal with frigid water and several hundred bucks in your pocket.
I don't need something for "frigid" water, jusst cold. I will rent for frigid, or go with a more tech oriented second regulator if I start doing a ton of cold water diving, I referenced this more because I could take it on the occasional dive in the Great Lakes when I visit home (in the summer). I have yet to dive Nitrox, but I would like to learn. Of course, from everything I have read, this concern is hypothetical, and hasn't ever actually happened (I could be wrong)
I like those who spend $1000+ on a Ti reg to save weight and then put it in 10lbs roll-aboard .
Though ScubaPro can be found worldwide and Atomic is more NA based I would not let the service issue be a deciding factor. As was said both first stages are work horses.
When we decided to replace regs 4 years ago one of the factors that lead us to atomics was the second stage size and design. The scubapro second stages IMHO are bulky. The other factor that I have come to appreciate is the interchangeability of the regs. All the regs have the same basic design with just a few differences. For instance, the only difference in the first stages are the materials. As for the second stages the main body is the same.
So what does that mean? Parts for one fit another. Have an old B1? for about $100 or so it can be updated to be a B2. Want a different exhaust like what is on the M1 buy it and throw in a Z2.
If I was teaching and in salt water a lot might hedge towards the SS version but otherwise the Z2, B2 or M1 work fine for most. And FWIW I have had my Z2s past rec limits on tec dives and in 45F water and performed just like the do in 80F water.
My bag is a 12 year old Sea Quest (I think, the name is no longer legible) duffel that doesn't weigh anything. This is not JUST for weight savings, I have sort of dreamed of getting a T2 for a while now. And I love state of the art anything, really.