Depending on your tax bracket, work match, potential average rate of return you could get a decent idea mathematically which one would be a better benefit...all using historical data not fluffy projections(imo).In most projections I'm guessing real estate wins because you wouldn't be asking this questions if you weren't confident in present/future earnings...so again it comes to personal choice vs risk (all retirement in one basket).

Is it purely a mathematical equation?

I probably wouldn't refi though unless it made a lot of sense mathematically.  

Mathematically, you as a borrower do not really see payment reduction by extending past the 30 year mark.

In the words of Lazarus Long (Robert Heinline, really): "Anyone who cannot cope with mathematics is not fully human.

On the one hand, there's plenty of math to go around... on the other hand, there's plenty of abstract meta to engage even the most mathematically-challenged amongst us.

Some of the foreclosures are getting bid up past what makes mathematical sense, so you just have to stick to your numbers.

Just don't necessarily take this advice if you are getting a free dorm room, as it wouldn't make as much mathematical sense

I'm currently working on a formula (with someone who is much more mathematic than me) for this transaction.My only question is: Would a hard money lender do this?

It is a mathematical equation so it can be adjusted in any market and with different inputs.