Just to make sure we are on the same page, the sum of the SV device's demand is 0.83A. The devices in my installation so far are:

These two always get power from the EFIS
GPS-2020 0.10A
WIFI 0.10A

These pull power from the SV-network
ADAHRS (primary and backup) 0.15A each or 030A total
AP-Panel 0.05A
Knob-Panel 0.07A
ARINC-429 0.10A
EMS 0.11A

Adding those to the 2.8 amps of the AFS EFIS is where I come up with 3.83 amps. In your post you state the EFIS rating includes all these devices? Or is it just the GPS and WIFI device included in the EFIS rating? I realize we are talking about a very small amount of amps, but I want to understand how the system operates to ensure my backup power design is robust enough.

Thanks for your time.