Fishless - Anyone keeping coral only tanks?

I figure coral only tanks are very few and very far between, but must exist.
Other than frag tanks at LFS which all seem to have at least
some sort of fish in the system, I don't recall seeing a coral only tank
with nothing more than a scant CUC as I'm currently doing.

Yes fish add personality, but add demands that coral do not.

I feed my coral, so have no concern for the lack of fish waste
other than happy with the lack of it.

Having just gone out of town unexpectedly, it was such a relief
to only deal with FW top off.

Curious to hear from others who are keeping coral only tanks,
how long term they've been doing it, and any down sides to it
and what they like most about it.