All of these things could be done with PowerDNS, but it would also require a number of other programs "helping" in order to get TLS and BGP, and the configuration would be a mess. With TentaDNS it's all in one convenient, easy to run place, with a single set of config, running multiple (even 10s or hundreds) of resolver configs all in one place.
That having been said, our Authoritative support (e.g. being the main nameserver for a domain) still lacks a lot of features, while our recursive support (e.g. being the resolver you use for your browser) is top notch.
What's a recommended way of using your product in a redundant way? PowerDNS for example has multiple backends, what I am missing is a bind style backend that is based on JSON files and is able to reload on the fly, so that I don't have to deal with a SQL database. Is this something that could be achieved with Tenta?
Additionally, if you file a feature request for JSON support in the bindbackend, we might consider it!
A lot of this sounds like rewriting the wheel in Go because Go is "hip".
Do one thing, and do it well.