Just my opinion...skip the Naui Master Diver cert and enroll in a Naui Dive Master course. I have the Master Diver Certificaation and have found that other than to me it means absolutely nothing and depending on where you live if you present the MSD card with $2.50 you may get a cup of coffee.
I had a very rigorous instructor/class and feel the knowledge and experience was great but if I could do it again I would invest my money in DIve Master training. Master Diver certification does not open any doors for you, it is basically a glorified AOW card from a cert presentation standpoint.
Part of the problem is that Master Diver means something different depending on the agency who provided the certification. Padi Master Diver certification is more ubiquitous do to the vast number of PADI instructors and operations around the world, their MSD is not difficult to obtain, in contrast to the NAUI course of instruction for MSD which is a specific training course....unfortunately nobody cares. With MSD you can't even assist with students in an OW course.
Dive Master training is much more beneficial in my opinion as it actually opens doors for you. You will learn everything in the MSD course plus other info. You will then have the option to help instruct AOW, at least the in water skills, and you can work as a paid guide/DM. This is a much more respected certification that actually means something other than being a piece of plastic that you carry in your dive log or wallet.
Again, just my 2 cents on the subject.
-Z