They're not your out of state investors, but they're the real players in your space.

Due to item 1, adding an ADU can require years to start achieving any return (once the accumulated cash flow recovers the initial negative position).4) ADUs detract from the existing structure whether this is privacy, a garage, or just yard space. 5) this is related to number 1, but there are many more buyers looking to purchase homes for their family than there are RE investors looking to purchase small unit count properties.

It has 12 dorm-style bedrooms and two bathrooms, plus lots of common space (TV area, kitchen, outdoor space, big basement storage).

The area I’m looking at is walking distance to the subway (blue line), near restaurants, etc. no parking but the apartment would have one space.

We already had planned to put in heat pumps in the main living space and in the upstairs between two bedrooms.

I have a need for additional office space.

Some people don't really vibe with sharing common areas and they need that personal space, and others thrive on always being around people and they don't mind sharing their snacks, so-to-speak. 

But I see multi tenant second generation space in secondary markets returning 8-10%.

Even more brownie points if it is tailored more towards the 2-4 unit multifamily space!

Being that it's a 2 story built on a single story platform reduces costs and labor because it's maximizing space.