Are there enough Property Managers with enough properties under management and deep enough vendors bench, or is it small shops13.

It's all the real estate agents, brokers and other vendors servicing landlords talking about how great it is. 

Hmmm... lets think about this and list just a few things that you are paying them for... tenant communication, owner communication, managing expenses, maintenance concerns, vendor communication, negotiating vendor pricing, rent collections, accounts payable, accounts receivable, tenant procurement, 3-day notices, 7-day notices, 1099s, accounting, and 24/7/365 MANAGEMENT OF YOUR PROPERTY, for pennies of the rent...

Some vendors present.

The irony is most investors who form LLC's do not operate them correctly, fail to obtain appropriate types or amounts of insurance coverage, fail to understand their coverage exclusions, take short cuts and don't obtain permits, use unlicensed and uninsured vendors,  fail to execute contracts with same vendors, don't understand the mechanism of additional insured status, indemnification etc. and are actually more prone to claims and conflict with their LLC than the individual who does not own real estate in an LLC but understands these tools I mentioned.

.* They have a vendor bidding system for all maintenance.

It seems so hard to find good contractors these days that are reliable and show up when they say they do.I just made a post asking how people find great contractors for their vendor list.

You don't know the law, you don't know how to handle difficult tenants, and you aren't local to work on it.This is what Ohio law says: “The tenant shall not unreasonably withhold consent for the landlord to enter into the dwelling unit in order to inspect the premises, make ordinary, necessary, or agreed repairs, decorations, alterations, or improvements, deliver parcels that are too large for the tenant’s mail facilities, supply necessary or agreed services, or exhibit the dwelling unit to prospective or actual purchasers, mortgagees, tenants, workmen, or contractors.”I would give the tenant a short, direct warning that they have 72 hours to coordinate with the vendor and set a schedule for repairs.

How many vendors they employ?

I've read the book "investing in real estate with no (and low) money down" and have been trying to find multifamily residential deals where the seller is willing to do a vendor takeback.