I work for a multidisciplinary practice which is owned by a hospital. We use NextGen practice management system with the integrated EMR. Because we've got a fairly large staff dedicated entirely to the development, implementaiton and training of the system, we run this software as efficiently as anyone else in the country who uses NG (we were finalists last year for the Practice of the Year award at the national NextGen conference). Overall, I am very satisfied with the product, but we've done a great deal of customization and development to get ourselves to this place.
Herbie, I've audited for surgeons who use e-Clinicalworks. I have to say that I am unfamiliar with the practice management system, but the EMR documentation is much more conversational than the data-driven language that NextGen EMR spits out.
Whatever you choose, don't ignore the fact that none of these software packages run correctly, efficiently, and specifically right out of the box. Unless you have IT staff that are specifically assigned to the project, you will need a consultant at the very least. We've hired multiple consultants since we implemented NextGen in 2005, to help us with gap analysis, setup, customization, coding and workflow. My employer could pay me for ten years with what they've already spent in consultation fees! But it has paid off, and we have a pretty well-running practice managment/EMR system.
The CCHIT has a list of "approved" EMR systems. They are really the only certification board for EMRs, (so there's nobody else to compare with) and they do not evaluate the interoperability of practice managment systems with their accompanying EMR systems. They only evaulate the EMR in terms of the electronic medical record, and those issues surrounding the record. They do not evaluate any coding capability, billing efficiency, reporting or scheduling. In short, plan to do some research.
Good luck with your implementation!