What are the flaws in my Co-op property management company idea?

[Jacob Sampson]

I dislike PM companies or at least the ones in my area.  Due to that I have been mulling over the idea of forming a Property Management co-op.  Essentially, I would find 5-10 other investors who also don't like our PM options.  We would use our pool of properties to keep a group of contractors busy full time or near full time.  We would have our own PM company without the 7-10% fee, the advertising fee, the first month rent fee.  I recognize there will be costs but drastically less.  

I currently manage my properties using a friend of the family that stays home with her kids but is interested in a little side work.  She handles, texts, emails, phone calls, and showing properties.  It costs me $1000 a year for her services.

Outside of that she passes all labor onto our maintenance guy that handles the actual work.

My challenge is if the friend of the family gets tired of it or doesn't need the money I will struggle to find a replacement and also, since I am sharing my maintenance guy with 30 other property owners there can be priority constraints.

With 5-6 owners and a pool of 100 properties, to begin with, my hope is we can create a heavily process driven company that is able to keep several contractors busy full time or almost full time.

We would focus on tenant communication, maintenance, filling vacant units.  We would not provide bookkeeping, reporting, legal work (although the actual details would be up to the co-op owners to decide).  

So far I have 4 other owners who have expressed interest in the idea (we'll see how interested they really are when we actually try to form the LLC). the 5 of us have a total of about 90 units

Thoughts?