We do a different version of BRRR it's Build - Rent - Refinance - Repeat.

If there is no difference between Carrot and WordPress when it comes to SEO and ranking on GOOGLE then it might make sense to go with WordPress for a long-term play. 

If you remodeled, added a room, replaced a roof, painted, boosted the curb appeal, etc. that's a different story.

Duplex have different zoning that may permit additional units.

LOL   That is exactly what I would expect from the Detroit City Government.If you go there, they are likely going to say you first need a license from a different office on the other side of town and when you drive there, they will say you need an appointment with them, but they only have appointments the third Thursday of each month.  

When an investor gets over 4-5 in a market then we normally talk about diversifying into a different market. 

The markets investors like you want to live in and invest in are often two totally different places, so don't limit yourself yo a single plan. 

The reality of the situation is much different than a spreadsheet. 

I had a different lawyer for my TN and my FL properties. 

As others correctly noted, as a landlord you must look at the big picture and if this happens to be a good tenant who has occupied the unit for a while, has a history of timely payments and has expressed interest in remaining at the property the value in an extension (assuming that is advantageous to you as the landlord) should be placed above your desire to collect rent in a certain method if this particularly tenant has strong desires to make their payments in a different manner....especially if the lease they signed allowed a different payment method.