I am an NHSC scholar
Just wanted to give you guys my input and it revolves around two things - Money v/s Freedom of Choice. ( this is of course making the assumption that you've all joined your respective schools because you genuinely want to take care of people - underserved or not - hence I am not going to dwell into the nobleness of serving in an underserved area)
A. Money - the reality is med school /dental school debt is crushing, especially if you're attending D.O schools. the cost of attendance at my school averages around 80k all 4 years. if you're doing a 3 year residency where you're making 50k most likely you'll have to put your loans on forbearance. so after residency you're looking between the ball park of 400 to 450k in loans. While that may not look like a lot - it really is.
http://www.kevinmd.com/blog/2011/04/real-life-medical-school-debt.html. NHSC does allow you to save a ton of money in the long run and being debt free is something extremely liberating.
B. Freedom of Choice (to choose your specialty and where you want to live after)
This is huge and a lot of people underestimate it.
While I love IM, Peds and Psychiatry, Neurology holds a special place in my heart. I can assure you when you've worked your butt off in med school and realizing that you don't have an option to choose when all your friends are choosing what they want to do isn't a pretty feeling. And here is the thing, with some exceptions, you won't know what you really really want to do until you've rotated through your 3rd year. And when you're finally done with med school and residency your priorities might have changed and would not want to live in underserved areas and put your life on hold (I grew up in a rural area - so I don't mind at all - but I'm not sure my future SO would be too keen to do so).
For me personally, the nobleness of providing care where it is needed while not being in 450k in debt while doing so gave way to the freedom to choose. (Luckily, I've come to enjoy Psychiatry a lot lot more once I decided that's where I am going to go)
What my life experience have taught me is this: be practical and find out what your priorities are. we all have to make sacrifices somewhere, and once you've made a decision be at peace with it. and consciously try to see past our natural propensity to see the grass greener on the other side.
Also if you're going to dental school - DEFINITELY TAKE THE SCHOLARSHIP! Unless you're going to be in the top 5% of your class, it is unlikely that you'll specialize. and 4 years living in a rural area, in my opinion, is definitely worth it when it comes to graduating with no loans.