I've been working on AppScale (https://github.com/AppScale/appscale), the open source implementation of GAE, which implements the datastore API, along with most of the other GAE APIs. Your app is portable to any other hosting environment if the need ever comes.

I have looked at AppScale several times in the past, but have never run it. Can you share any experiences using it in production?

You mean Datastore. Yeah.

I kinda like Datastore though. Maybe I'm just use to it. The limitations just make sense if you want to scale.

They also have a RDBS you can use though ... I've never used it.

Still haven't figured out a clean way to do geospatial stuff with Datastore, so that is one big caveat.

I'm not sure what you're doing, but using GeoHashes on GAE worked pretty well for me. http://en.wikipedia.org/wiki/Geohash

What did you do to get around the grid adjacency problem, where adjacent points can have different prefixes?

> The main benefit of say Heroku is that while migrating away is not trivial, in principle you shouldn't have to rearchitect your app to do it.

How is that an advantage over App Engine, given the existence of AppScale? [1]

[1] http://googlecloudplatform.blogspot.com/2013/09/appscale-bri...