From a pure decency perspective, it's unforgivable for sponsors to not communicate to their investors. 

It’s great that you’ve already started practicing with NOI and cap rates for evaluating properties, but you're right that smaller properties, like quadplexes or less, are often valued differently.For residential properties with four units or fewer, the market tends to focus more on comparable sales in the area rather than purely relying on income calculations like cap rate.

Assuming this is purely for investment sake, $55k on a $615k property isn’t a good use of your $$$.

From a pure numbers perspective, it appears to be a very good deal.

I'm at a point where I can afford almost anything I want, but I still have to consider whether it will really bring me joy or if it's just a temporary impulse for a shot of dopamine.

Its not real complicated, its purely a math question.

If you're buying it as purely an investment property - project for a 20-25% down payment.  

If i were to be a billionaire, i wouldnt mind to put 1 mio in a pure speculative bet.

I am not familiar with Philly or the technical questions you pose.I am thinking of this from a purely investment aspect.  

Hey Ben - welcome to the joy of investing!