If by outsourcing PCI compliance entirely, they mean "ensure you don't store cardholder data by tokenizing it and we store the real stuff" this is very much not a new solution, so I'd struggle a bit to see the value of a new entrant.
There's already quite a few payment gateways where an e-commerce site can iFrame the payment page (or similar) to ensure that they never see the real cardholder data.
(the fact that this shouldn't really make them out-of-scope for PCI is a different problem)