Doesn't you local DNS server have to query other DNS servers to resolve requests anyway?
You can put hosts file on RAM disk.
With some servers it's also possible to save and reload caches.
Assuming you're not doing hundreds of thousands of new lookups (sites you've never visited before) every day, it's very easy to configure a system for yourself that is faster than any open resolver.
There is one trade-off: if sites switch IP's without telling their users (preferring instead to wait for ttl's in open caches to expire) then for those sites that like to hop from IP to another unexpectedly, you need to monitor for this. This is rare though, and you can try to safeguard against it by "pinging" less oft visited sites periodically, but it does happen occasionally.
As for reliability, if you lose access to your "professioinally-configured endpoint" you're SOL. You can't do lookups (assuming you don't know how to do them by hand). Meanwhile I'm unaffected.
I would not have done this for myself and tell you about it if it wasn't faster. I'm not gathering info on users or selling anything. I'm not telling you what to do proclaiming I'm an "expert". I'm just an end user, like you.
When you use an open resolver, you are sharing a cache with everyone else who uses it. Some might do nefarious things to the cache.
When you use a resolver listening on 127.0.0.1 you are sharing it with whoever can access localhost on that port. i.e., no one (hopefully)
"professionally-configured" C'mon. You sound like a marketer's dream. Be a hobbyist. Be a hacker. Experiment. Thinks for yourself. Or don't.
How much time have you devoted to learning how DNS works?