While I'm sure it would be nice to have a druid mana tracker built into agUF or whatever other unit frame you use, it's been asked for many times and has never gotten a response from anyone who actually works on agUF/<insert unit frame mod here>.
And really, is there something so horribly wrong with using a standalone addon to provide a class-specific function? Just use the one you linked in your own post. It doesn't have to used Ace2. If it works for you, it's fine.
Well using stand alone mods is just fine! but when i start having bugs like now its annoying like hell!
if it can be done then why not?
a simple request and a simple answer! Yes or No!
and i do agree with grita!