By effectively utilizing space, we can often increase the number of units or functional areas within a property without expanding its footprint.

Also the school districts have been increasing property taxes in A LOT of investment properties thus eating some of our profits. 

So, my first caution is it would be healthy not to expect similar results on certain real property investments/deals in the current and near future cycles.That said, there are multiple considerations and clarity needed, before I would act on any investments with your equity.

I think you're missing another point-- if rates increase.

Having toured some of the most prestigious, expensive and historic estates and properties from Brookings to Astoria, there is still considerable investment opportunity at the very high end of the luxury market.

If private companies continue to provide the insurance, I suspect we will see further increased premium costs which will need to be reflected in the rents tenants pay (all tenants: LTR, MTR, STR).  

Thank you for your time and consideration.

With your primary residence, things can be pretty straight forward in terms of splitting mortgage interest, real estate taxes etc. on your returns.If you go into a rental property, there are a lot of considerations to think about.

Ability to repay - can you as the borrower afford the payments based on the loan amount.Typically they will not take into consideration the mortgage on a new property that has not been taken out as that is new.

Quote from @Deirdre Lizio: This is not an "either-or" consideration.