Hey wschang812,
I'm finishing the GSBS masters now, and did it in 1 year plus a summer also. I re-applied to dental school immediately before starting the program, received interviews to NYU, Tufts, and Columbia after academic update, and will be attending Tufts in the fall. I was originally planning on doing the 6 credit transfer as you mentioned, but I highly highly highly recommend you plan your course load as if you're going to do all 30 credits while in the program. The reason is because even though UMDNJ lets you back-transfer the dental credits to your masters to get the masters retroactively, most dental schools I spoke to required that I completed the masters in whole prior to matriculating. I therefore planned to do the 30 credits in the 1 year + 1 summer and am glad I did, because even after I was accepted to Tufts they didn't allow me to waive any of my masters credits. In fact, at my Tufts interview I had to show my course schedule to demonstrate that I would be able to complete the masters before orientation in August.
Now don't worry, if you pick your courses right, you can easily do what I did: 12 credits first semester, 13 credits spring semester, 5 credits summer. There isn't an official 'summer' though, as many of the classes start and end at different times and the latest ones are simply called 'summer' classes even though they're still technically part of the spring semester. My 'summer' class is virology, which 3 credits, one month long and ends June 30th. So that's when I'll be done, meaning I'll have completed all 30 credits in less than 1 calender year. My other 2 summer credits is the research rotation, which you can do whenever you feel like it. If you talk to Tsiagbe he's very relaxed and isn't afraid to frankly tell you which courses are harder or more work than others.
This is a very useful program if you use it to well and pull a good gpa. As I said I applied right before the start of the program as a re-applicant. Therefore at the time of my application my app simply said I was starting the program, but didn't have any grades yet. I pulled a 3.8 my first semester, and within 2 weeks of academic update, had 3 interviews. Good luck.
Acceptance is not very competitive BUT this is not a downside. It means that how much the program helps you is entirely dependent on YOU. If you simply 'pass' through the program it will have done very little for you. If you can pull off a 3.5+ gpa, while taking at least one of the 1st year dental courses, and get the rest of the cards in order, you can do quite well. I think this is an underrated program, and did more for me than my informal post-bac classes I took prior to it.