What other factors would you consider?

And this does not even factor in the last few deals we closed for our clients!

There are a million factors here. 

Definitely, have only one kitchenThe second meter is a factor if you are attempting to represent a portion of the property as an ADU.

BTW, we love this market because we've got a major university a few blocks away, Fortune 500 employers in the area and other factors which drive constant rental demand.

Payments that you make normally fall into one of 3 buckets100% of the payment can be factored in somewhere on the returnPartial payment can be factored somewhere on the return0% of the payment can be factored in somewhere on the returnHouse-hacking also has considerable tax implications in the event that you want to sell this property.You can potentially defer a portion or all of the gain on the investment property with 1031 exclusion.You can potentially exclude a portion or all of the gain on the personal residence with section 121 exclusion

It depends on a few factors IMO in which route you take.

I think with all of them, the biggest factor is making sure expectations are set correctly and that your FIL is able and willing to lose his entire investment is things go wrong.  

Getting over the fear factor was the first step.

I'll factor that into my analysis going forward!