I have and use the POD HD beanie. I think it's awesome, and while there probably are "better" devices out there (read: Kemper and Axe Fx), for straight up amp tones the POD is more than adequate IMO.
I've tried some external IR's (yes, Redwirez) with the POD but i didn't exactly got blown away, for me the sound didn't grow some serious balls in an instant. I thought it sounded a little bright, it certainly has a better high frequency content than the stock cabs, but I wouldn't want that high end in the mix anyway. I usually put on a low pass filter on guitars around 8-9k anyhow... The stock cabs got a whole lot better when the cab controls were added in version 2.0...
What I do though is running a dual amp setup and mixing two cabs in the POD. MeAmBobbo's guide is excellent, and if you haven't read it I strongly suggest you do. There are some great tips in there.