We discussed IBR in the other thread:
How to save over $100k on your student loans
My conclusion was that on a pharmacist's salary, if you make the 15% IBR payment for 25 years, you can completely pay off a loan up to about $220k, so nothing gets forgiven at the end. Also, if your interest rate is 6.8% it's already pretty bad, and by stretching it out to 25 years, you will pay a ship load of interest.
Actually, I just realized that the government had it all figured out so that very few people will get anything forgiven under IBR (besides PSLF). There is a lifetime limit to the amount of federal Stafford loans you can take out, and thus there is a limit to the loans you can put on IBR. For health professional students, the limit is $224,000. Notice how close that is to the $220k I calculated that you will pay off after 25 years on a pharmacist's salary?? Well actually GradPlus loans may add on some more on top of that, but then there are cost of attendance limits as well.
The limit for undergrad students is only $31,000-$57,500 depending on certain factors. So even with a $40k salary, you will probably pay that off before 25 years. The people you hear about with hundreds of thousands of dollars in loans from just an undergrad degree or even worse, a career college certificate, have got to be taking out private loans which are not eligible for IBR.