Your plan looks a lot like my panel.
My audio panel is up high. It almost never gets touched, except when swapping Comm1/Comm2 or listening to Nav for ID.
My GPS/NAV/COMM is under the audio panel where it is very visible and on the same visual level as the pilot's EFIS. This allows my eyes to travel back and forth from the EFIS to the GPS without having to visually search for the GPS. It may sound silly, but it's a fact that the eye goes back and forth horizontally a lot easier than going diagonally.
As others have mentioned, you will use the Knob Panel the most, so it goes right next to the EFIS. All adjustments to the Knob Panel are indicated on the EFIS, so it is convenient to have the EFIS and Knob Panel right next to each other.
Next to the Knob Panel is the Autopilot Panel. You will use this panel often to set up your navigation method, so it should be easy to reach.
I put my Comm2 radio (the Dynon) on the far right of the three panels. I can push frequencies to the Dynon Comm2, but usually I just dial frequencies in as ATC gives them to me. The freqs are indicated on the radio panel, so visually, my hands are operating where my eyes are looking at the freq screen. I use my Dynon Comm2 as my primary radio, and use my GPS/NAV/COMM1 as my backup radio and for picking up ATIS while staying on COMM2 with ATC.
I built this panel about two years ago. It's the third panel I've had in this plane, and is the result of all of the good and bad things I've found with my prior two panels. I've been really happy with the current set-up, and will probably build an exact replica of this panel for the RV-14 I'm building now.