I bought this one...
They offer the same basic brush with gravity feed, siphon/jar feed or with a combination feed sort of like the Aztek brushes where you can switch back and forth. They also offer essentially the same brush but in a more traditional trigger button form. I really liked the pistol grip and thats part of what sold me on it. I was able to demo one of these at a show and in 2 seconds I was spraying very fine 2-3mm wide lines with ease.
I assume the Grex compressors are good but I have an Iwata compressor. Grex and Iwata are compatable so you can use the same hoses and fittings.