I agree--doing IBR makes sense from a couple points:
1) While in IBR, your interest doesn't capitalize. That could save you thousands, or tens of thousands, over the life of your loans. It all depends on whether you are able to stay in IBR as an attending (ie., you interest may never capitalize again if you go into a lower paying specialty). Even if you go into a high-paying specialty, you're still saving a few years of capitalization (saves you quite a bit), and then if you have a high paying specialty, you can pay off all that interest before it capitalizes, as it capitalizes when you leave IBR (which if you time your application right, could be a year after you finish residency--plenty of time to pay off interest before it capitalizes--though you may as well just apply all that extra money to your highest interest loans/principle)
2) While in IBR, you can make more than the minimum payments--and you can apply those extra payments all to your highest interest loans first. So you save money by selectively paying off your highest rate loans (granted, you can do this if you put your loans in forbearance)
3) If you do IBR, the government will make up the difference in the interest accrued on your subsidized loans that your monthly payment doesn't cover, for a max of three years. That should save me a few thousand over my residency.
Basically, no one knows about the future of programs like loan forgiveness via IBR/PAYE--there's a threat right now with people concerned about proposed new changes. But we do know that right now the government will pay for your unpaid monthly subsidized Stafford interest that accrues, and it essentially "pays" you by not capitalizing your interest if you stay in IBR (make sure you always reapply on-time!). Given that IBR monthly payments are easily affordable for most residents (assuming you don't have five kids, live in NYC, etc.), then I think it makes a ton of sense to enroll in IBR and get those benefits. When it comes to finance, whether we're talking about loans or taxes, it literally pays to know what the government "pays" you for, and that can save you a lot in the long run. Especially when you owe a lot of money.
One thing to keep in mind is if you file your taxes with your wife jointly, then IBR takes her income into account as well--so your payments may be more than $380/month. On the other hand, if she owes money as well, that gets taken into account. You could always run an analysis, but I'd imagine IBR plus paying extra so that you pay $1500/month in total (with the non-IBR payment all going towards your highest interest loans) would save you money over paying $1500/month on your highest interest loans, even if your IBR payment is double or triple that $380/month because of your wife's salary. Preventing capitalization can really save you a lot!
Unfortunately there's no way to prevent capitalization when you start repayment (interest will capitalize at the start of IBR--just not again after that as long as you're in the program).
