Awesome! Another NY area local diver... come dive with us, if you are near NYC.
I think that the 40 is such a common standard in our area (where people use them for deco and bailout), that unless you are really planning on flying a lot with your pony, you will find it easier to buy a 40 used (and sell later if necessary). Plus, when you are slinging the bottle, the difference between a 19 and a 40 isn't very noticeable, and I think that the 40 actually hangs better.
Plus - more gas! Always a good thing (see the last 6,000 threads on this topic).
I did just join you guys!! I actually dove Dutch spring with you the other weekend. You where kind enough to help me with my leaking LP hose. Thank you very much for that again.