The new class will bring faces from far and wide, definately worth working on the monk imo,
The balance and issues are a never ending battle and will never be perfect.
I think the team have the right idea but execution and time frame are vital to achieve the most beneficial of outcomes,
New class gives you
+new players, +interest existing players, +publicity.
Fixing balance gives you
+x% happines of current players and -x% happines to those who feel hard done by.
New content (needs to be high level content) gives you
+interest level of existing players, %+ drive for lower levels, x amount of returning/new players.
So i would personaly;
Launch monk +100 user count,
2 weeks later (announced at monk launch) release new items (copy paste jobs of current but with defensive stats included e.g reinforced osr AC 0-3, reinforced gpfb amc 0-4. Also making current of that item more common (happy gemming)
2weeks later launch new content where said items are required.
So you gain user count, maintain it with "lazy" but necessary defensive copy paste items, prolong and drive user count with new difficult content.
Ideally level requirement floors as not to alienate everyone,
Floor 1 everyone, drops very very rare, floor 2, 40+ x2drops still super rare, floor 3 45+ x2drops again, still rare. Floor 4 50+ More common, potentially exp boost per floor too, so +1k per mob per floor.
Another "razarus moment" was only going to type monk is a good priority :/