Okay I'm bored. I made the spreadsheet for you. For all purposes let's assume you could apply for an unlimited amount of cards to total a 73000 (need the credit limit to cover any balance transfer fees and the top end of your income falls in the 25% tax bracket.
Assuming you could payoff your 70k@6.5% loan off by YE 2017 in equal payments of 3385/month. In total you'd pay 4441 in interest. With an expected refund of 1110 on your tax return from student loan interest deduction. With a 3% BT fee, if you moved all your loans to CC's you would pay 2100 in fees at the start.
So net after 21 months you'd save $1230 or $58/month.
Risks:
Falling off track and paying 23% interest on the BT balance at the end of the 21 month period. Job loss, expensive car repairs not saved for, forced move, lots of stuff could cause this.
Missing or late payment (can even be caused by autopay messups) triggering a switch to 23% balance within the 21 month period.
Is the risk of falling off track and having to pay 23% interest per month worth saving $58 a month? Only you can decide!
Wow! Thanks so much for taking the time to do the math. I had done some already, so my math was a bit different. I can't pay in equal lumps, so I am starting at $1,700 per month and by the end should be at around $4,500 per month. This is due to my current salary, and my scheduled raises over the next 1.5 years (in my contract).
In my schedule, I would pay $5,115.30 in interest, which makes the delta a bit bigger.
However, you are right that it is a lot of risk for potentially small reward. If it was $10,000 I would feel more strongly about it, but saving $2-3,000 is not enough when compared to the risk of getting caught at 15%+.
I'll have to look into doing some smaller lumps, or just try to refinance using a normal lender to get a better rate. There is also the option of a no-fee balance transfer on a different card, but I'd have to look into if I could transfer my SL to it.
I appreciate the time you've taken to help me decide!