We have many customers using AppScale in production. Some migrated away from GAE for very specific reasons. Privacy (particularly in Europe), lock-in, control, performance and cost are the typical reasons...in that order. Many, however, come to AppScale because they love the GAE development model and want the independence to run their application wherever is best for their business; without the restrictions, quotas and performance irregularities.
The brilliance of GAE is the development model. The notion of concentrating on the business logic, the problem you are trying to solve, rather than working with stacks of software is the innovation. Our customers, and GAE's, are typically not tech companies. They do not have a deep bench of experienced developers. They are fashion and electronics retailers, global non-profits, SaaS companies trying to rapidly prototype and create MVP's. They want to innovate quickly and fail fast as they develop their business model. This is where the GAE model shines. It's fast. Business today must move at the speed of need, and the App Engine model, whether GAE or AppScale, is a tool that facilitates this.
AppScale is a complement to GAE. If want to run in AWS, SoftLayer, Azure or Digital Ocean, no problem. You can also run your app behind the firewall on OpenStack, Eucalyptus, CloudStack, Mothership1 or simply on top of KVM or VMware. AppScale is easy to install and deploy from GitHub. GAE needs to worry about running 4.5M active applications (up from 3M last year) but AppScale only needs to worry about one application, yours.
We understand that GAE did not make many fans in the early days. That has changed and their 50% growth in active apps over last year is evidence. Add AppScale to the picture and you get to continue using the awesome development model but you have the complete flexibility to run where you choose and maintain complete granular control over your app.
So, I will make a bold offer. Check out AppScale and give it a test drive. I would love to hear your feedback. If you need some extra love, our engineers will help over our IRC channel at freenode, #appscale
It is our goal to be the open source private PaaS of choice for forward-thinking developers and companies. We would love your support.