Well, I am employed and have neither of the degrees you mentioned. I've been continuously employed since graduating. 

You should be employable following your M.Arch.  If not... seek a refund.  More paper and letters after your name won't automatically move you forward if you don't know the profession.

How about for building your own practice?

i think an MBA would only be useful after you have had at least 5-7+ years of architectural practice getting really great, rounded experience, and are afterwards in a good position to start your own firm anyways. OR maybe you want to take on the business aspect in a larger corporate firm.

An MBA won't teach you how to run a professional practice (any profession).  The main thing it will do is acquaint you with basic concepts of finance, marketing, etc. that you didn't get exposed to in high school or architecture school.  It will improve your mindset if and when you get into a management position or decide to go into business for yourself.  It probably won't mean much in the job search or client search.  So, if you can take cheap courses or seminars or whatever in business without going the entire degree route, it is worth doing.  Much of it can be self-taught for less $$$.  If you want to move into a different part of the building industry, such as construction management or real estate development, then the degree might be worth the expense and effort.

Education is like any other investment.  You have to weight the costs and benefits, and don't be afraid if you conclude it isn't worth it.  Contrary to popular myth, education isn't priceless.  It's a commodity like anything else.

Thank you all for the comments and advice. I was looking at Yale's joint degree program and thought it might be efficient to get MBA exposure while the student is already there. This means that the student won't have as much experience in just the architecture profession before doing an MBA, but it can lower costs and time spent for the degree?

I've been applying to part-time MBA programs for the fall of 2017. An MBA can absolutely help with your career. You mentioned networking, management and financial training - I would also add leadership and communication skills. A lot of my clients are MBA graduates - I'm hoping it will help relating to the and gaining credibility in their world. 

As others have said - you should definitely work for a few years before embarking on an MBA.

cr3sc3nt: If you have not received all the responses you desire on this topic I suggest that you you do a keyword search on the forum for "MBA" - this is a very common topic here and there are quite a few earlier threads that cover your questions in great detail.