We currently have three other rental properties and rent a studio out in our primary residence.

Have you thought about house hacking or buying something with cosmetics as a primary? 

The primary residence thing every 2 years isn't really an option. 

Could you rent your primary and move into a new multifamily to save expenses that way, then move out in a few years?

In my opinion, the primary reasons are financing and appreciation.Generally, you're likely to have trouble getting financing for investment properties here.  

Well, excluding the single family home that I am planning to rent out in NC in the next week which started as my primary home, this truly is my first multifamily home purchase with an intent to invest.Now, to answer your question, is it wise?

Additionally, this same lender can run the numbers for you on taking out a HELOC on your primary to see if all costs are covered from your investment property. 

The negative aspects out way the positives in most cases given our current technology (even for a primary residence).

However, I've come across one potential issue that I'd like to clarify.I've read some articles suggesting that in Oklahoma City, it's not possible to purchase a property without using it as a primary residence.

And if you win that auction, there is still a primary lien attached to the property and the old owner.