Times and times again, they'll tell you the latter and actually choose the former.
The same bargain as paying more to have no ads: people vocally push for no ads, some will ponny up the money, and the vast majority will make do with the ad supported model, while ad blocking or giving up on the service when they're fed up with it.
> Does a customer care more about how long payment processing takes or do they care that it takes their local mobile payment app?
I'm curious how you find the people to ask that ? If your current service doesn't provide support for the payment app, who would you ask if it was a deal breaker for them and refused to become your customer, not giving you anybof their information ?