rsync alternatives for large mirrors?

[Mike Loseke]

 Anyone here ever use or see any tools (free or commercial) that are 
similar to rsync but maybe provide a little more in the way of reporting 
features? I'm looking into some possible alternatives to a system I have
scratched together using rsync. I'm bumping into some issues involved
more on the backend of my system (stats on directory structures and
contents) which is limiting the amount of data I can sync in an 8 hour
window to about 120GB. I'd like to be able to sync 300GB+ in the same 
timeframe and still get my backend tasks completed.

 Currently those backend tasks that are eating up a fair bit of time 
consist of doing a "du" like action on the trees at either end which is
used to generate a report which can be referenced by users so they know
when data is in sync. Ideally I'd like an "update as you go" sort of
method but I haven't figured out a way to do this with rsync. I do use
rsync's output stats in addition to my own.