We are a fairly new service and our early users and bringing new use cases. We are listening and trying to expand our service to meet your needs!
We have a couple of users that are trying to emulate over 1,000,000 users. This overwhelmed our implementation. We have increased the size of the servers we are hosting on Amazon. More importantly we just released yesterday a major upgrade. We have replaced the stat collection with a new Java service that uses SQS to post to the database. In the initial version we wrote directly to the database and it was just not fast enough. Now those are posted to a queue and updated in a more efficient manner int he database ensuring we capture everything and do not create a bottleneck.
Watch for more enhancements. And let us know your needs!