@DFauvre I owned both the Helix Floor, the Axe-Fx II, and the Axe-Fx III. I sold the Helix.
With the Helix, their 2 line, pseudo 4 line grid is very limited in its implementation. If you want to implement two drive pedals in parallel then summed and feeding two amps, you just used up all 4 lines of your grid on the Helix without even able to do parallel effects. Axe-Fx II and III don't break a proverbial sweat doing this.
Helix drive block lacked a wet/dry mix control for the 3 years that I owned it. It also lacks a way in the block itself to mute audio when the block is not engaged, which is a must have for parallel drive processing. There's a way to achieve the same muting in the Helix using path volume levels, but it's a clunkier implementation.
The Helix modulation and delay blocks lack EQ sections in most of the models. Fractal has had that since I started using them on OFW 10.0 on the Axe-Fx II.
The firmware update implementation for Helix is clunky and bricks many users' units. They still haven't gotten that down like Fractal has. They also don't do incremental updates for bug fixes, be prepared to wait 6 months or a year for some bugs to be fixed.
The modifiers section of the Fractal is far beyond anything that Helix has been able to implement to date.
The amp models in the Helix feel like they have training wheels compared head to head with the Fractal, the sound is more compressed. You really need to battle with the Helix to try and get close to the feel of the Fractal amps and you will never hit the nail on the head.
If you like using Variacs in real life, you can do that on the Fractal. For Helix you are SOOL as they really have no desire after 3 years of me begging them to implement one.
The Helix stock cabs sound like ass compared head to head with similarly named Fractal stock cabs.
Pitch tracking on Helix just blows chunks compared to the Axe-Fx III. Expect to hear a lot of bad tracking and splices with Helix.
So what were the positives of Helix?
- More dedicated bass drives.
- More dedicated in name bass amps (though the tweaks one can do in the Fractal makes every guitar amp into a killer bass amp)
- Some Strymon-esque mulit effect reverbs available in one block.
- (Edit) Line 6 exclusive model of a modified Traynor YBA called the Cartographer. And their other original called Badonk. Those were the best feeling amps in the unit.
- Billy Sheehan's Pearce preamp model in the Helix was a thing of beauty that I haven't had luck replicating in the Fractal. @FractalAudio can you please get one to model?
- They have a drive block supposedly modeled on a Klon. But the Fractal FET block with some mods again outshines it for feel and sound.
- Integrated foot controller on the unit.
- On the fly sample rate conversions.
Depending upon what you are looking for, my recommendation is the Axe-Fx III.