Minor terminology nitpicking: SEPA is just "Single Euro Payments Area", you're speaking about SEPA direct debit specifically.
These concerns still apply to direct debits, unfortunately. The reason being that there's barely any authorization for direct debits, you just need the bank account number and name. Isn't the situation somewhat similar to CC transactions without 3D Secure/whatever it's called? I seems to recall reading in my bank's terms that I can chargeback transactions for something crazy like a year. You always need a "mandate" to debit an account and if you get that properly signed by the customer, you should be able to get the bank to reverse the reversal, but I can appreciate the bureaucratic overhead.
I was only offering it as a potential solution if getting people to sign up is genuinely difficult.
The thing with PayPal is: they offer direct debit to customers and I'm assuming that's how most people who would've otherwise used direct debit directly with you ended up paying. It is my understanding that PayPal is also aware of the risks associated with this and offers merchants the option not to accept payments through it. I can't seem to find an article just now, but I remember instances where PayPal told me something along the lines of "this merchant does not accept payments via direct debit, please use a credit card instead". I can only assume this is because they at least partially pass on the risk.