Mark, Badger now makes an airbrush with a gravity cup that will swivel down
for a siphon feed by attaching a bottle. Can't recall, but Iwata may have
one as well. I have Pashaa, Badger & Iwata airbrushes, single and double
action. All are siphon feed, ie from the bottle. As I paint exclusively
acrylics, I use the Iwata Revolution or Badger Antham 155, which have needle
designs for Acrylics.
I have heard folks who prefer the gravity feed vs siphon. Not sure you will
get a clear answer.