What you want to do only makes sense when you don't understand what the protocol is doing. Relays aren't single point servers. They're more like download mirrors, except you download the file from all of them simultaneously, verify that the file is the same for all, and just keep one of the copies. 

There is a cost to adding a relay, in that there's more copies to download and discard and more to upload, but the advantage is that a single uncensored relay can overcome millions of censored ones. And since your relay list is public info by default (including read/write status) anyone who wants to hear from you can just check the same relays you use. 

Maintaining a copy of all of your own notes through a self-hosted relay is a great idea, but only using that relay would cause significant problems with zero benefits. You don't even gain enhanced privacy.