New ways of doing things are great, like my pay as you go pricing model. However i have found that whenever you make these kind of innovations, it takes a LOT of explaining or people get confused very quickly. This has meant that my innovative pay as you go pricing has basically lead to some abandonment that i didn't really expect.
To resolve this, while keeping my pay as you go pricing model i've now introduced hybrid pricing, so you can either pay per site as you go, or take a traditional pricing plan of x number of sites so you know what you'r paying up front.
The interesting thing is, although fixed plan pricing is actually more expensive up front, customers are liking the idea a lot.. So i'm seeing conversions growing already within days of implementing it.