Key Challenges and Considerations – What are some common challenges or things to keep in mind when starting in real estate as a side business?

And if risk is the biggest consideration then you'll be wanting to focus on quality of tenant more than quantity of tenant.  

Your 11 year estimate on how long it will take to recover my capital does not take into consideration an average 5% increase of rents per year.

What is your ceiling height on the ground floor? 

According to planning, only 1 and 1/2 story is permitted in this neighborhood.There are some consideration yet to be taken at this point.

Plus, equipment can be a hefty expense and may need repairs over time.Instead of a conventional treadmill, I would consider a walking pad paired with a height-adjustable desk-- its cheaper and can be hidden/discreetly tucked away.

One consideration is your expenses are higher and you do have the cost to furnish, so it's not all sunshine and roses, but if you buy it right you can do really well.

On another note though, I see first hand how they treat the places that they rent, and upon taking into consideration the rehab on each turnover could potentially cancel out that additional cash flow they would bring in.

I will definitely take your points into consideration!

If you expect to refinance in the near future, I would take this into consideration.