I never had a problem paying via debit card when I used them. I don't have any active droplets with them right now, but I've always paid with my bank issued debit card, and looking at it now it's still the active payment method on my account.

I've been using my visa debit card (europe) without problem since more than a year ago

They also don't accept prepaid cards since they've said 80% of fraud cases involve prepaid cards. Linode took my money and worked well but they don't have a $5 price point.

I've always used a debit card to pay for my DO server and it's never been a problem (although it's been maybe a year since last time).