Was having a fun, purely academic conversation with someone and somehow the topic went from the stock market, ETF's, to real estate, to BRRR's and either he or I or both us came up with this and wondered is this a legit strategy that others have used?

Aside from the tax benefits listed above, they get to enjoy the properties with their families during their down time.

If you have any questions feel free to reach out I enjoy helping and talking REI.

Mostly owners that are tired of the grind and want to retire and enjoy life.

That looks like your problem - only 3% down (can you get that conventionally if its a pure rental property - i'm not 100% but I don't think so) - with that leverage (97% LTV), pretty much nothing is going to pencil.

I really enjoy it, and so does my tenants.

In other words, how would I calculate the return (from a purely financial standpoint) of "investing" in a primary residence vs renting and putting the money elsewhere (perhaps even into an investment property, but also considering buying a business)? 

This is because the properties are cheap enough that landlords cash flow immediately, and they also get to enjoy the perks of having the college students around.

If you're making a big move like this it would be wise to make sure you live as close as possible to where you plan to invest.Beyond that, simply being open to the idea that you may not enjoy living there and acting accordingly would be my best advice.

I enjoy helping new investors learn the new programs and loopholes.