I have the Amplifi FX100 and the POD HD 500.
IMO POD HD 500 it's oriented to pro musicians. It sounds better, but it's more difficult to program, and more expensive. More realistics amps and effects.
The Amplifi FX100 it's very easy to program, it's perfect for your fist fx, and to play at home you can have a lot of fun, recommend to semi-pro musicians, more cheaper, it also sounds good, but POD HD500 it's better sound.
I use POD HD500 for live and i don't use any amp, it sound great. I have an amp behind me, but i was connected to PA. People thought u was using the amp.
The next gig i will try Amplifi FX100 to test it.