With SedoPro there are more detailed stats available like top referers, geographic breakdown, domain trends etc.
You can also set different optimization keywords for each country/market.
These tools are useful for optimizing domains (you can get a better idea of where visitors are coming from and what they are looking for).
Here is an screenshot of the domain stats: http://img45.imageshack.us/my.php?image=pureog1.gif
I think a number of these features may have been introduced in the 'standard' Sedo though.
As for revenue it's difficult to say how much more you get vs Sedo standard. I have no precise figures.
You will also be assigned an account exec.
Requirements: own at least 200 domains and/or $200 monthly revenue.
Check my sig if you need an invitation
SDS pretty much sums it up.
Re: Revenue - Sedo used to guarantee at least 10 percent more revenue if you move to SedoPro. Reason enough to try. You can PM me for a code as well.
See also: http://www.sedo.com/sedopro/unique.php4