You had me thinking about your setup on the Devo 7 since you wrote you enjoy adjusting the Devo software.
As you know I'm using the Devo 10 but the 7 should be the same.
Forgive me, when I first read this post, I had forgotten my Naza-lite setup.
I haven't used it in several months now. I'm flying with the full Naza-M V2.
Well, I do have a clean FS on the FMOS switch using the naza-lite, see below.
This is a joint update about IOC and FS.
IOC is awesome in and of itself.
You can free up that IOC switch (mixed) and use it exactly as intended.
(I'm assuming you haven't extensively used IOC yet, most people haven't)
as it can mentally break up your orientation and cause a crash.
But that is only because it takes practice, like learning to fly period.
Q. Why use IOC? A. Recovery without FS.
IOC used as it is designed, once you can fly with it. Sometimes my birds loose video and I no longer know my orientation.
I do not want to land and in most cases do not need to initiate FS. No matter what the orientation of the craft is once IOC is activated.
Elevator stick back means the craft is coming straight back regardless of the nose direction...
As with everything else this is if you have properly calibrated your home point before take off.
You are the center of IOC once initialized.
I saw this video 2 years ago and have been using IOC ever since. Before understanding IOC I crashed while in IOC. This was because I knew nothing about flying or configuring my equipment. I had wired a dedicated IOC port for a gimbal tilt. yeah... CRASH. Now intrigued by this I began researching IOC.
Sometimes I'll fly an entire mission LOS in IOC just to stay sharp with it.
But it pays for itself in a real flight situation if I loose my orientation.
This is my post that got me deep into understanding IOC and led me to the above post.
Ok, here we go... you can copy your working program to another blank program number to experiment on the Devo7.
Call it 'testioc" or whatever works for you. Put the IOC switch program settings back to the original state.
Test this in the Naza Lite config software.
To use the FMOD Switch for FS on the Naza-Lite (you'll say, I knew that!!

)
Under the Function menu; Travel adjust; adjust your fmod sw range to stop on FS.
You may need to adjust the 'Sub Trim" to get all of your modes centered.
When correctly done you now have GPS, Atti and FS using only the flight mode stick.
Your IOC should be good and you get a clean IOC port again.
You can then use a mix for FS using an unused sw on the Devo 7, You should have maybe two free switches.
The D/R switch (front right) and maybe that Hold sw on the top left. The 10 doesn't have that the switch at all. But by doing this, no mater what mode you are in you can activate RTH... independent of what mode you are in. You may need to adjust the trim as well.
Just an idea for learning and continued experimenting...
personal footnote:
One thing I don't care for on the Devo 10 is while adjusting a mix I need to back out of the mix setting to see the change.
I don't think my DX9 disables control while adjusting mixes.