The application is working beautifully for me.
I used it already when it was in beta (and free during the beta) and immediately got a licence when it made it to 1.0.
The application corrected numerous problems I had (duplicate calendar events because of the Entourage/iCal mess, duplicate contacts, contacts with the same e-mail, etc) and it fixed everything like a charm.
Since then, my MobileMe syncing is much smoother and weird warnings I was getting all went away.
The application is a real blessing for me.
I haven't seen problems with memory on my Mac.

I find it a bit pricey, but at the end, it saved me from so many headaches that I thing it was well worth the price.