Depends what you want to be when you grow up.
I'll disagree with Kostas on the value of a master's degree: if you want to keep doing science, and you don't mind doing science that interests someone else, then you really don't need an advanced degree. A master's degree is essentially worthless in the marketplace, as evidenced by the fact that the average salary with an MS degree is only slightly above that of a BS with comparable experience and is far below that of a PhD.
If you want to keep doing science that interests you, then the PhD is the entry ticket. It is possible to succeed without it, but it's an uphill climb.
If you're not sure you want to be a scientist when you grow up, then the job you describe is a good entry into the business side of things. The growth path then is likely to be in sales and/or management rather than science. A PhD isn't necessary in this case (an MBA may be more useful).
I've think that research (on the one hand) and applications/support work (on the other hand) require different personality types. In research, the premium is on thoroughness (the old joke about learning more and more about less and less until finally you know everything there is to know about nothing). In applications, the premium is on quickness .
I long ago concluded that I don't have the patience to be a good researcher (I have the attention span of a three-year-old), and I've seen too many good researchers wash out of applications work because they couldn't handle the need to come up with quick answers and then get on to the next problem. You have to look at yourself and try to judge where you fit on this deep/quick continuum.