As long the payment isn't done by the payment processor, you never can be sure.
Just now I am in trouble with one sponsor. I got my payment by time for more than one year. And now, suddenly not payment coming in and I also get no response from this sponsor. Waiting for 6 months already. His sites are still on and getting updated. Also the sponsor program is still on-line.

So you see, risk you will have always.

But if I see a program runs by nats or mpa, I trust them more. People using this software are more serious and trust-able, but it's still not a guaranty.