I've been using an RFX MIDI Buddy (later switched to a MIDI Wizard) with my Kemper and it works great for me in performance mode.
Since it has 10 patch buttons, I have immediate access to 2 performances (10 presets) at a time.
I have noticed a very slight lag when going between performance patches, so I try not to do that in the middle of a song.
Otherwise, I have 2 banks, a total of 4 performances, that covers all the sounds I use.
I have one of the switches set up for morphing, and the other one I use for 2 momentary switches.
One switch is set up a lead boost (which I can also do using patches, but usually it's easier to use the momentary).
The other is set up for either a phaser or a flanger, pre distortion, which I only use in a couple of spots in my set.
I did program Sonar, which runs my backing tracks, to also be able to send automation for patch changes in my Kemper, but I never use the automation track. It just kinda felt like cheating a little. No offense to those that use it.... I definitely get the appeal, especially for someone playing metal...... that's a whole other level of concentration there, buddy!!