As for your "better off in the stock market" comment, your analysis is flawed because it is based on an equal cash vs cash assumption.

. ($400k new building minus $50k taken already equals $350k)

My father wants to use his SDIRA to provide a loan to the LLC him and I are equal partners in.The loan would provide the additional funds we require to purchase an investment property.The LLC would pay principle and interest at market rate to the SDIRA.Would this be considered a disqualified transaction? 

They always have the winning bid until the bid equals or exceeds the debt associated with the property.

The PM company charges a fee equal to first months rent for this lease only service.

With the state of Oregon we are all equal partners individually but the properties have different LLC names.

Yet, even Chicago has had its share of backlash from the PURE IDIOCY of thos so-called wanna-be 'financial experts' that advised & counseled equally foolish and future-vision incapable HUD staff members in Washington D.C. ofcs.  

Now assume you buy $350K home; put $25% down and take loan at 6 3/8 on $262,000;  Your payment is $1630/month or you're losing about $600/month all things being equal. 

How many surgeries the hand surgeon has to do to equal the commission of a $1,000,000 home sale? 

If they are VERY professional, they will have their processes in writing as verification that policies are enforced equally and fairly by their entire staff.6.