Custom Rom Backwards Compatibility

[GuyGotMadNameGame]

Hi,
I am running the Android N firmware on Athene: Custom Rom RR_5.8.0

I was playing around with dual boot, and successfully, but I only tried the 7.0/7.1.1 custom ROMs.

Could I flash MM custom ROM to dual boot, or simply put, can I downgrade to a MM ROM without messing with the N firmware, with and without dualboot on separate occasions or do I need to flash stock MM?

Does it sort of have a backwards compatibility?

What sort of risks will I be looking at?

Thanks in advance, this community is wonderful!

 

[zeomal]

Could I flash MM custom ROM to dual boot, or simply put, can I downgrade to a MM ROM without messing with the N firmware, with and without dualboot on separate occasions or do I need to flash stock MM?

You don't need to flash stock MM.

Does it sort of have a backwards compatibility?

Theoretically, the ROMs should not have any issue.

What sort of risks will I be looking at?

From what I've seen, ONE person had some issue with fingerprint recognition on MM after flashing an N ROM. Otherwise, I've encountered nobody who has had issues.