Backuping selected directories

Hello.

I would like to make monthly backup of selected directories from network HDD 3TB to USB HDD 2TB.

I tried

Supersync - but Its veeeery slow - it is analyzing about 3 hours.
Superflexiblefilesync - but it stop working for me and still failing after startup.

But both these apps dont allow me to skip the same files but with different time or date. And becouse somehow almost every files on my 3TB HDD is changing date, i have to copy everything over and over again. One image of selected directories take about 36 hours

Dont you know some better solution?

Im backuping on:
Macmini 2008 - 2GB ram, osx Lion
1000GB ethernet for 3TB HDD
USB 2.0 for 2TB HDD

 

Shame on you... So good information, so quicky and shortly

Thanks!