I think you can trust them.
Just got a mail from AlertExchanger today:
Your order : 928-c99e1d-1342727199636-387109 has been completed.
If you've found our services helpful, please don't keep us a secret; refer us to your friends and partners.
Thank you for doing business with us and we look forward to serving you again soon!
And the money has appeared in my Liberty Reserve account without problem. The transfer took like 4 business days.
Thank you AlertExchanger for your great service!
Now I can start investing and monitoring finally...