The headrush models have been tweaked and improved and are quite good. I actually have owned a Kemper, AX8 and a Helix so I thought I would chime in as I have spent many hours with all 3 units. Out of the 3 units the AX8 and Kemper to my ears were better sounding than my Helix on pretty much every amp model. The AX8 had incredible modeling and the reverb was lush. The Kemper was great as well but I hated that you couldn't really tweak it like a real amp. With all of that said the unit I kept is the Helix. The reason why is simple. I love the interface the scribble strips and ease of use. I also find the effects to be really good. If the Helix had the same interface but the modeling of the AX8 I would be over the moon. In the end I just found the design of the pedal itself outweighed the slightly better modeling of the other units but I feel you pain :).
P.S. Line 6 buy Fractal and steal their modeling lol