The upside is, you don't have to claim the rental income as long as it goes into your retirement account.

We're retired, so what's important is cash flow. 

As you may know, pulling money out of your IRA before you are 59 1/2 subjects you to paying income tax on that money PLUS a 10% penalty.However, the good news is that if you are buying your first home, you may pull out up to $10,000 from your retirement funds without incurring the 10% penalty (it is one of the handful of exceptions to that rule).If your IRA is a ROTH IRA, then you will not be subject to any income tax either because you've already paid the tax on that money when you put it in.If your IRA is a Traditional IRA, then you will have to pay the income tax on it, subject to your rate including any other income you have as well.  

I followed the path I was taught since grammar school: go to school, get a job, live below your means, save your money, retire.

If I can borrow at 5% it seems to do this as much as possible until I retirement nears or I plan on needing cash.

You going to retire!?!""

Investor benefits by using his skills of finding a property and structuring the deal.Private lender benefits by using idle cash in his retirement account to fund the work.Owner benefits because he would get more $$ agreeing to JV rather than selling at the discount. 

If my goal were to retire at the new retirement age of 73, then I would probably hold and see what kind of appreciation it would get over the years. 

If only we could deposit paper we all would be retired by now;).

I'll be happy to provide help to any questions when it comes to self-directed retirement accounts (especially ones with the checkbook control).