So I've had my HD500X for a little over a month now and I spent quite a bit of time, of course, creating usable tones that I like. I've used the POD with headphones, computer speakers, my Vypyr VIP 2 amp, and more recently, and old Crate PA/Mixer system that my parents used to use years ago and have now given to me. The Crate PA system really brought the tone to life and allowed me to get the tones dialed in the way I like them before using the POD live (although my wife wasn't happy about how much space it takes up ).
I have to say that with the HD500X, my tone was the best it's been since I was much younger and used to use a Crate G120C amp when playing live.
I play lead guitar at church, and I've been using my Peavey Vypyr VIP 2 amp with a Sure SM57. I love the Vypyr amp, and with the SM57 off-axis, I was able to get some decent tones live, but the problem is that the stage volume became an issue. The Vypyr doesn't have a line out, so I had to mic it, which would normally be fine, but In the church setting, if I turned the amp up loud enough to get a good fat mic'd tone, it would overpower the bass and keyboard players because of speaker beaming, and be overpowering in general for a church service. If I turned it down to keep that from happening, I'd end up with a good, albeit quieter, tone on stage, but the mic'd sound coming out of the PA was thin and weak because of not having enough volume for the mic to pick up a good source sound.
So after tweaking and learning the POD for a month, I used it at practice and during the performances this past weekend. It made a huge difference in my sound. No longer having to worry about being too loud or too soft was great, and the tone I got through the PA system was the best I've had playing here. I used my Crate PA system and one of it's 2x8 speakers as a monitor, and placed it in front of me pointing away from the audience but toward my ears so that I could hear it pretty well without it being too loud.
All in all, it's been a great experience and I'm pretty excited about using it from here on out.