Really quick, once you hold Title in an entity you are ineligble for conforming residential conforming loans. 

Legal entities are not able to qualify for conforming residential loans.

A residential lender should be able to offer a 30-year or 15-year fixed-rate refinance loan on a 4-unit provided you have enough equity in the property -- and especially if you're under the high-balance conforming limit.

For example out here I recently gave a ballpark cost on two separate rezones...one was in conformance with an existing general plan and would implement the desired future zoning, another was not in conformance with an existing general plan and would require a land use plan amendment as well as a community plan update to allow the desired rezone to proceed...the first rezone's ballpark cost was $10K for submittal with an anticipated final cost of ~$100K once you include the 3-5 other consultants needed and responses to comments ect, the second one's cost was ~$40K for submittal with an anticipated final cost of ~$250-300K once all consultants were included...I know some locations a 'rezone' is a way the City brings a property to the desired future zoning and it isn't nearly as costly, but that is why the 'story' is more important than the question...

The fed tax gets differed and you pay 85% in 2028 -assuming you keep it for the full 10 yr period;( program was stated in 2018) State tax will depend if your state is conforming or not. 

Legal entities such as LLC's are not eligible for conforming residential loans. 

Also, they usually can originate a conforming long term loan...  

The Survey is focused on conventional, conforming, fully-amortizing home purchase loans for borrowers who put 20 percent down and have good credit. .Los Angeles Airports Stalled.

I also didn't want to give up the superior financing rate/terms with conforming loans, but I now realize that missing out on even one deal over their restrictions cancels out the benefits they offer.

Yes, if I'm getting all that, there were two issues, that a seller will finance because the property will not conform to conventional financing requirements and the opportunity to earn interest income above the profits of what a conventional sale would be.Another reason for the seller to finance is to spread the tax liability over the loan term avoiding a lump sum tax amount being due in the year the property is sold.