I use the same setup as you with my MP! and don't see why you wouldn't want to upgrade the AC firmware. I choose to ignore the controller updates as they seem to restrict some flight areas that are not a concern to me where I fly. Besides, I do more flying using Litchi than with the controller for mapping and survey missions on my property.
And be sure to Use DJI Assistant to update the battery processor on each of your batteries too! I just got two certified reconditioned batteries that are DJI-branded in DJI white open-box packaging that I need to update. Seems like a small bother but I don't see why it would be bad.
Others might chime in with their own take, so listen and use your choice of how to go.
Happy flying!