I can the of 10 other things you could waste your money on. seriously, I don't understand why people with Prof. degrees want even more education. youll be in school longer with lost wages lost experience, Unless there is something you are dying to explore at a particular school, don't just go to go. if someone else is paying for it well then i guess why not but if its out of your pocket, make sure you are getting something in return out of it besides another degree.

In a short term, I don't think you'll get any benefit from getting MArchII, other than your personal satisfaction... but in a long run, it might help you to "wow" your clients (some clients just want the name... beats me). Well, you can establish good connections with some starchitects, if you can have them as studio professors. You can also get teaching jobs with masters degree.
If you don't have to worry about money, then I don't think it'll hurt to get MArchII (I need money, and that's why I can't do it).