IBR is the smartest thing to do. You will always qualify for IBR, even at attending base salaries. Your monthly payments will go up, thats all.
There are 2 options in terms of income base repayment: IBR and pay as you earn. As of right now, pay as you earn is the best option. Some of the perks are: for 3 years, the stafford loans will continue to be subsidized. Just google Pay-as-you-earn and you'll learn plenty.
In terms of the public service loans, as long as you are IBR, working at a "non-profit" hospital for at least 10 years, you will have the ability to get your loans forgiven. Most academic hospitals and most community hospitals are non profit.
The biggest question is, will this public service forgiveness still exist in 10 years. This was implemented in 2007, meaning that the first round of physicians' loans won't be forgiven until 2017. Who knows if the government will get rid of this by then since most physicians will qualify under this requirement (because again, most hospitals are non-profit)?
So bottom line, it's is always the smartest thing to start making payments on your loans.