If the DNS updater is actually updating, then on a WAN IP address change it should update for you.

This is the entire reason we started using Mikrotik. We got tired of having issues and 'guessing' if devices were actually checking for changes and sending updates. With Mikrotik you put in the script yourself, so you can define exactly what it's doing, when it's doing it, and see logs of what happened.

FWIW we use DynDNS, it's worth it to not have to worry about it. The worst thing that could happen with them is we forget to update our CC info and they delete our account. :)