So old post but it still pops up #1 on Google search
Ran through this at a buddy's place...not impressed. Essentially the same amp lineup as the HD500 with some noticeable upgrades but nonetheless at the end of the day...it still sounds like a Line6 version of an amp.
My two cents...If you want simple setup, an unlimited choice of amps and a great sound right out of the box then Kemper's the clear winner.
If you want to spend hours nit-picking your routing and effects, you want an unlimited choice of amps and a great sound then Fractal's the clear winner.
If you want hours of nit-picking your routing, using the same amps that have been modeled for over a decade (the same exact amps BTW), months and months in between updates and an alright sound then Helix is your go to. Congrats, you've saved yourself $500.