I have the Badger 360 which is both gravity feed and siphon feed and a 175 also.
The 360 has a small built on color cup that I use when I just want to touch something up, or just spray a fairly small amount of paint. Its really amazing. a few of drops of paint and you can spray a small part or 2.. i've also used it at low pressures to attempt to do fine lines for camo recently.
but overall I perfer the convenience of the siphon feed because I'm less likly to spill paint on my project. I use model Master paints and I have 2 siphon lids that fit those bottles so I can thin them right in their bottles. (one i made myself and the other I got from Micro-mark) I also have a aztek 2.5 cc color cup I converted to siphon feed for those small jobs when a bottle is too much and don't want to mess with the color cup.
And as for the metal cup with the angled siphon feed that came with my 175, well i've never used that thing...