Where can one find resources on employee-owned companies, especially in how they compare to other types of companies, profit-wise?

One place to start would be to locate a good public business library or university library where you can access computerized private company databases, such as those from D&B, Hoovers or BVD (Bureau van Dijk) to name a few. These allow you to specify company selection criteria and then to download financial data from those selected into a spreadsheet. The Risk Management Association (formerly known as Robert Morris Associates) also publishes financial benchmarking data on small/medium businesses.

The Best places to start are:
1. The National Center for Employee Ownership in Oakland, CA (http://www.nceo.org)
2. The Ohio Employee Ownership Center in Kent , OH (http://www.oeockent.org)
3. The University based Research program at the Rutgers' School of Management and Labor Relations

A couple of additional ideas:
- Profitcents is a subscription data base with great information on companies in many industries
- If there is an industry association for your business, they frequently do comparative financial surveys that they aggregate and will provide non-company specific information that you can use to compare your business to.

Assume you are referring to and Employee Stock Owned Company. I was previously the CFO of one (and huge supporter - in that company's case there was no doubt that it was more profitable due the ownership). Another excellent resource is The ESOP Association http://www.esopassociation.org/ a great non-profit resource. Good luck!