I would still go with 8 ohms, unless there is a risk of your kids blasting the system while you are out and not keeping an occasional eye on receiver temperature.

Note that AFAIK nobody on the boards has run M80s on that Pioneer, so there is a risk the two will not be happy together.

M60ti, VP180, QS8, M2ti, EP500, PC-Plus 20-39
M5HP, M40ti, Sierra-1
LFR1100 active, ADA1500-4 and -8