Ask HN: Does anyone use hosted API management tools (3Scale, Apigee, WSO2, etc)?

We have an API-based SAAS that runs functional browser tests for our clients. We're currently in Alpha, and we're exposing our API through AWS API Gateway. We're manually provisioning API keys and associating them with users, but before we enter public Beta, we need a self-serve solution.

Does anyone have experience with any of the hosted services that provide auth, plans, subscriptions, registration, payment provider integrations, billing, etc? It would allow our (small) team to focus on the core product rather than rolling our own.

I'm currently assessing 3Scale, Apigee, and WSO2 Cloud - but I'd be interested in anyone's experience with any services like this.