He discussed the numerous pros to hiring a company in the beginning.

Your in over your head with that many properties, I have been to numerous Philly auctions and there is a sea of people who will just outbid you to the point it’s not even a deal. 30 properties is not feasible and chances are half of them won’t even be auctioned that day.

There are numerous part time agents in this area doing in excess of $3 million annual volume.I know this comes down to my own goals and risk tolerance, but do any of you have an opinion or advice when deciding who to go with?

That property has been for sale for a while on numerous sites. 

While they're great and have invited me over numerous times for a beer and BBQ, I don't want to blur the lines of our Tenant/Landlord relationship.

Real Estate is a competitive game, and Internet and BP have leveled the playing field for anyone who wants to take advantage. 

I would always contact a CPA in this field. 

Along the way the GC and subcontracted plumber mentioned numerous times that they found great news or thought of more efficient solutions (i.e. the mainline plumbing under the basement was intact--that they had assumed was all broken and needed replacing).

They could be unsavory for numerous reasons (as an extreme they could be child molesters or drug dealers).  

That said, I figured that I might get some good feedback from all of you to save me some trouble or at least help me narrow down the field!