How much power is enough power?

I had just enough power before the season 2 patch with the ability to effectively solo all bosses up to Pink Bean and I was satisfied with it since I could bring my friends along for more fun. Now? I might time out or get killed fighting even Czak, a boss I used to finish in less than 5 minutes. I say that's enough because I'm not putting in any more money.

I would also not fund any other class as most of the others have some fundamental or stylistic weaknesses that I can't tolerate.