You have to realize units are all on one huge spectrum, not static points like tank, off tank and dps. She will have her moments but I don't think she gets much use due to how narrow her application is (reasonable dmg and tank stats, expensive to deploy even in role, gets better when kept in a certain health threshold). If you can afford the UP and use her in a rough spot to hold a choke at threshold a lot then she's a great unit to have. She's probably more useful if your healing core is weaker or lack a "real" tank (Bernice, Gellius, Deine).