Privately-held versus Publicly-traded Investment Banks

In the course of work for a client, I've had some discussions with senior executives at a decent-sized, privately-held investment bank. Since the company is privately-held, of course I don't know exactly how well it is doing, but judging by how it has expanded and made a lot of new hires over the last couple of years, I'm inclined to believe the company's executives when they say their investment bank has been doing well and has avoided the problems that have plagued larger, publicly-traded firms such as Lehman Brothers. I wonder whether this is true more broadly of privately-held investment banks, and whether there has been any research conducted comparing privately-held investment banks to their publicly-traded counterparts with respect to their stability, ability to manage risk, etc. Perhaps it's simply the case that firms with less capital available are forced to be more prudent in how they employ that capital. Perhaps there are relevant differences in culture between publicly-traded and closely-held investment banks. I do remember reading that this was a concern of some Goldman partners before the firm went public in the 1990s.