The rationale behind the reason that brokers encouraged buyers to get two loans instead of a single loan with PMI was IMO that PMI is non deductible so getting two loans allows you a better deduction.
However, I would bet that as you intimated, if you run the numbers, you may very well find that a single loan with PMI actually saves money for the buyer, especially if you account for origination fees of a single verses two loans. I think each case would vary depending on the strength of the buyer and the prevailing rates of the time and of course the broker.
In terms of simply qualifying for the loan, I don’t see how there would be any difference at all. In each case you would have to disclose the exact same information to each underwriter. So if you got the dual loan case with a single lender, or a single jumbo loan with PMI with that same lender, or a conforming loan with that lender and a second with someone else, the underwriters would all get the same information so I don’t think that would have bearing on whether the buyer gets approved or not…
No factual evidence in that response… just me guessing so I would surmise that someone will ring my bell and prove me wrong…