Hi Dennis, I am not Phil, but from my short time of owning the HD500X and then trying out the Helix, the Helix is a major improvement. However the overdrives and high gain are still not as good as the AX8 IMHO. The Helix does have far cooler bells and whistles and an expression pedal and easy to program from the unit. Tempting. But I have decided to stay on the waiting list for the AX8. But the Helix is FAR better on several levels than the HD500X.
my .02