Flown with both and never had an issue though I never need to check in bags and have traveled on my todd so never needed to pay extra to book a seat.
I even once stood my seat down at the gate when asked for a volunteer to do so. Had an extra day in LA, very posh hotel for the night, $24 breakfast voucher and a $500 voucher with Spirit.
Was booked in a regular room at the hotel and the receptionist said “oh a voucher from an airline? We’ll tell them the regular rooms were booked so I’ve put you in an en suite room.”
Bingo!