I own
https://rya.nc/, but hadn't used it for any important email. After an issue with the registry caused some extended (over a week) downtime, I don't ever plan on using it for email.
Potential issues with obscure ccTLDs:
* Search engine penalty outside that country.
* Limited registrar support.
* For a really obscure ccTLDs like .nc (only a few thousand registered), the TLD itself will be a cache miss in many cases. This makes initial name resolution very slow (hundreds of ms).
* Various ccTLDs require a local presence. If you're not a local, you'll have to have it owned by proxy. This can be expensive. There are only two companies that will handle this for .nc.
* Smaller ccTLDs may be run locally with no off-hours staff. Timezones may be an issue if anything goes wrong.
My personal email has been on a .org for many years, and I haven't had problems with it, other than the generic problems of trying to run a small mail server. The "guilty until proven innocent" style systems run by a few major problems are infuriating. If you don't send enough proven non-spam, your mail goes directly to junk. If you run a vanity domain somewhere like FastMail, you probably won't have this problem.