I think you first have to look at the guidelines for BofA Principle reduction program. It requires that you be applying for the Government HAMP Program.
Also, please note that the maximum principal reduction they are offering is 30%, and the Loan to Value ratio cannot be under 100%. For example. You bought your house for $400,000. The maximum reduction could be up to $120,000( new amount of $280,000), but if home values are at $300,000, then the most they will drop it to would be the 300K.
So ask yourself, if you were applying for a loan today - what would you honestly be able to afford that? If that amount is not in line with the Old loan principal minus the 30% reduction(if you qualify) then there is no point in seeking the reduction.
Like mentioned before - Talk to the bank directly before paying someone upfront for a "Promise" of a principal reduction. I hope the numbers make sense and you can keep your house, and if not, then Short Selling would be the best option.
Good luck and update the post with the outcome. Thanks
Short sale Specialist