I have been a Kemper owner since August 2017, primarily playing live as I work as a professional musician in Canada. The Kemper has not once let me down in terms of reliability, and with the exception of one sound guy who didn't know how to EQ his FOH (he left me a note saying "change tone on Kemper...sounds thin" which I thought was hilarious) I have always gotten compliments on the sound of the unit no matter where/who I play with.
To preface this discussion, I play primarily country music, and my scope of use is limited to this genre for the most part, with a little rock sprinkled in for good measure. I've been fortunate enough to play a ton of different capacity events ranging from 100-6,000+
I started hearing rumblings about the Quad Cortex (QC) when a friend of mine who is also a professional musician picked one up and began raving about it. Availability was an issue, and when I finally decided to order one, it took well over a month for me to get it.
Initial impressions after using Kemper for so long was the QC was super easy to pick up and use, the out of box presets sounded pretty darn good, and within about 8 hours of tweaking on the QC, I was able to set the Kemper aside and gig with the QC full-time. It goes without saying that the UI of the QC is really what draws people to this unit. I suppose it is comparable to a Helix in some respects, but being able to physically manipulate the chain with your finger is really an underrated aspect of the unit. Coming from the small little monochrome display on the Kemper, the QC makes a guy feel like he set foot into the 21st century.
For what it's worth, I have done almost all my tweaking on Kemper by using the in-unit display and knobs on the profiler. I know I could have a better UI by going into Rig Manager on my computer, but I wanted to learn how to manipulate stuff on the Kemper really, really well so that if I needed to make changes at a show, I could do so between songs if necessary. I even went so far as to rename all my patches and such using the control knobs instead of attaching a keyboard to the unit (I suppose I'm a glutton for punishment). I originally set foot into the modeller world with a Digitech GNX4 back in the day, and I owned a Helix for about a month before going the Kemper route as the Helix was extremely unreliable (footswitch issues).
The QC is built like a tank, something to be expected from a supposed "tour ready" piece of gear that cost me over $2,500CDN, the footswitches are responsive and having rotary control knobs built into them is another aspect that takes the UI to a level above Kemper. In fairness, the hardware Kemper is using is well over a decade old now, and by comparison it STILL doesn't lag that far behind newer units, a testament to the R&D the team at Kemper put into this unit!
The QC is a bit more compact than my unpowered profiler + remote that I lug around in a Gator Kemper Transit bag (coming from a pelican 1610 wheeled case), and the portability aspect is something that is definitely helping me see past a few of the gripes I have with the QC.
The QC is still very much in its infancy, and I don't have a similar comparison with the Kemper as I came into the Kemper world much later, but some of the grievances I have with the QC are stuff that - because modelers are so common now - you think they would have ironed out before rollout of the product.
Here's what I've noted as my main grievances so far with the QC:
1. The Kemper allows me to switch patches during a live show by initially showing me the options to select from BEFORE it switches away from the current sound I'm using...The QC immediately selects the next bank and if I have it in scene mode and I want a solo patch, I now have to do a foot dance in order to select my solo preset and hope that I don't select the wrong one while I'm also trying to solo at the same time. Extremely frustrating
2. The Tap Tempo button on the QC doubles as the tuner button, but you have to hold down the tap tempo button to access the tuner, taking about 3s of time for it to activate. The Kemper remote has an instantly-available tuner button that immediately mutes my guitar, giving me quicker guitar changes between songs.
3. I CANNOT bypass the cab block on a certain output (like you can with the Kemper), meaning if I want to run stereo FOH into a guitar amp for stage volume, I would have to re-do all my patches on the QC to have another row that bypasses the cab block for my given "monitor" output. Again, something that can be fixed but is a bewildering issue because the routing options on the QC are otherwise superior to the Kemper IMO.
3. Last night when using the QC at a gig, I had the tuner/tap tempo footswitch become completely non-responsive and I had to reboot the unit to get it working again. FWIW, I had just updated the unit so it may be a bug in the code that needs to get sorted out... I have two more shows in the next two days so I will see if that issue arises again with the QC.
4. The QC features a "gig view" which is sort of similar to the "perform" mode on the Kemper and alters the display and behaviour characteristics of the switches and such, but the QC doesn't let you default to gig view as of yet, meaning if I have a throw-and-go festival gig and I forget to "swipe up" on the display to access gig mode, I will have to do it mid-song. This is something that can easily be fixed and has been brought to the attention of NDSP.
5. The Kemper Remote's ability to have a stomp section as well as a preset section is GREAT for live use, and the QC has not implemented this feature yet. It is something I used every time I played live with the Kemper
Sound-wise, I think both units sound great, with the edge going to the QC as it feels just a bit more realistic to me. This combined with the portability of the unit has kept me from just returning the QC altogether, and I can see myself continuing to experiment with the QC as my only modeler for the foreseeable future. I still have the Kemper and I'm on the fence about keeping the QC, but again the product is super new, and I knew there would be growing pains.
In the electronics world, there is a saying that you should "buy something for what it can do now, not for the promise of what it may be able to do in the future", and if you're of that mind, I think the QC is not there yet for situations such as mine. However, I find it kind of fun experimenting with a new piece of gear (however frustrating) and noting bugs and other issues to hopefully help improve the product as time goes on.
I hope my long rant helps clarify some of the usability issues with the QC, but also highlights the fact that the Kemper is still totally fantastic and a good buy despite newer modelling technology on the market. I didn't mean for the post to come across as a s*!t talking of the QC, but I wanted to be as objective as I could be after having such a high standard set by the Kemper for my use case.