The one thing I believe to be a great factor is true real-life experience.  Adding the certs and education are a plus.  Certs in some cases may show that you know about the topic.  But showing that you applied those skills in an environment is key.  Education gives you the skill set.  But then again...applying to an environment adds!

Just my $0.02.  

Have you done a sort of ROI analysis. How much will cost a Master and what it will bring you???

Also, depends what kind of Master you'll do. I have done a Master of Engineering (here in Canada) and it was course based. It was interesting, but the level was more general. For some of the courses I can say that I had to study more for CISSP than for the course itself. Others (like cryptography) went deeper in the math demonstrations but they lacked the practical side.

You can look at offers for the type of job you are looking for. If they are asking for a Master - do it, if not... depends of the price. Mine only cost me 4500$, so it was a good investment, but if it will cost you 30.000$ I will carefully choose the school and the speciality.

I plan on getting both.

I think all the right points have already been stated but I'll just say my view on things.

When it comes to certifications vs degrees I look at ROI, time required (which is a component on ROI anyway...) and what opportunities it is likely to open up for me.

A case in point when I was younger I dropped out of Uni. It didn't actually hurt my chances of getting into an IT job, largely because in my country degrees don't mean a whole lot when it comes to infrastructure implementation and support. However I am past the stage of being new in IT, proven my mettle of being able to handle difficult tasks and I want harder challenges (work for an enterprise!) but I know I am not going to get those opportunities without a degree.

So while I got my foot into IT with a fist full of certs and a burning passion which was evident in my eyes. I am now facing a glass ceiling. One which can only be broken by putting in years of experience on my CV, so that I can get past HR and get an opportunity to speak face to face. I am hoping a degree will be more time efficient for me instead.

Luckily enough I want to get into security and in my country, there are enough oldschool geeks who don't have degrees who still run the security scene here. However I want to travel and I understand that this is not how it works in other countries and therefore a degree can be very important.

In the end the deal breaker for me before I do any educational content is this.

A) Is it fun? If it is, I want to do it regardless
B) Is there an immediate opportunity or reward that I can leverage upon getting it. I'm not talking about I may get a raise, or I may get a promotion, or I may get a better job. I'm talking you get the cert and you get that raise, promotion, better job.
C) Is the degree/cert something to be proud of? I'm VCP #51337. When I got my VCP number I though it was l33t.