I worked at Cornerstone Research full-time
The people are great and the compensation is strong. The culture isn't bad and folks are genuinely interested in your development.
The hours can be long during busy periods, which is an inevitable but notable part of the business model. There really isn't a way around it.
Advice to Management
Keep doing what you're doing. The place is well run. That said, try to resist the temptation to bring in more projects during super busy periods.