In my experience interviewing candidates, an MS counts for less than a good undergrad. I find that software engineers with foreign undergrad and US MS are often missing some fundamentals.
So we're talking about spending ~2 extra years in school for basically a nil result when applying to development jobs. My personal anecdotal experience observing those around me is that getting a MS in CS is leaving a lot of money on the table - you will give up 2 years' salary and your salary upon graduation will be the same as, if not lower than, an undergrad with 2 years industry experience. Do it if you love it, but know that it's a financially negative move (and substantially so).
The big gap I see is Ph.D's. When interviewing Ph.D's for development jobs (i.e., you're writing code a lot of the time) they consistently do poorly. I see a lot of poor code discipline, bad architecture, and all in all poor engineering. They know algorithms and data structure inside and out, but when it comes to writing solid, maintainable code, a PhD in the room is in my experience a disappointment.