@murat IMHO merely "owning" your data in a managed SaaS database is not enough, especially because there is nothing you can do with that data at the moment if you want to leave. It may solve GDPR-type questions about personal data ownership, but practically speaking you're still totally locked-in.
That being said, they did say they plan to support migrations in a reply to my GitHub issue, which is great. I still wouldn't use #Wildebeest until they actually do of course, but it's a good sign!