I have looked into this extensively and 1 point that has not been discussed is the personal guarantee that is typically given on commercial loans. If that is indeed the case and you give a personal guarantee, than the secondary market treats that the same as if they are still under Fannie/Freddie guidelines. In other words they will count against your 10 property limit. The "wiping the slate clean" will not apply. Lenders who have posted here care to comment.
See below
Limits on the Number of Financed Properties
If the mortgage loan being delivered to Fannie Mae is secured by the borrower’s principal residence, there are no limitations on the number of other properties that the borrower will have financed. If the mortgage is secured by a second home or an investment property, the multiple financed properties policy applies. The maximum number of financed properties that are permitted is based on the underwriting method, as described later in this topic.
The financed property limit
applies to the number of one- to four-unit residential properties where the borrower is personally obligated on the mortgage(s), even if the monthly housing expense is excluded from the borrower's DTI in accordance with B3-6-05, Monthly Debt Obligations (01/30/2018);
applies to the total number of properties financed, not to the number of mortgages on the property or the number of mortgages sold to Fannie Mae;
includes the borrower’s principal residence if it is financed; and
is cumulative for all borrowers (though jointly financed properties are only counted once).
The following property types are not subject to these limitations, even if the borrower is personally obligated on a mortgage on the property:
commercial real estate,
multifamily property consisting of more than four units,
ownership in a timeshare,
ownership of a vacant lot (residential or commercial), or
ownership of a manufactured home on a leasehold estate not titled as real property (chattel lien on the home).
Examples — Counting Financed Properties
The borrower is personally obligated on mortgages securing two investment properties and the co-borrower is personally obligated on mortgages securing three other investment properties, and they are jointly obligated on their principal residence mortgage. The borrower is refinancing the mortgage on one of the two investment properties. Thus, the borrowers have six financed properties.
The borrower and co-borrower are purchasing an investment property and they are already jointly obligated on the mortgages securing five other investment properties. In addition, they each own their own principal residence and are personally obligated on the mortgages. The new property being purchased is considered the borrowers' eighth financed property.
The borrower is purchasing a second home and is personally obligated on his or her principal residence mortgage. Additionally, the borrower owns four two-unit investment properties that are financed in the name of a limited liability company (LLC) of which he or she has a 50% ownership. Because the borrower is not personally obligated on the mortgages securing the investment properties, they would not be included in the property count and the result is only two financed properties.
The borrower is purchasing and financing two investment properties simultaneously. The borrower does not have a mortgage lien against his or her principal residence but does have a financed second home and is personally obligated on the mortgage, two existing financed investment properties and is personally obligated on both mortgages, and a financed building lot. In this instance, the borrower will have five financed properties because the financed building lot does not need to be included in the property count.