Differential mirroring?

I like to keep my portable apps on my PC, as well as on my pendrive.

This way I can use them in day to day work, as well as when I am on the move and don't have my computer with me.

This obviously means I need a robust synch program to keep me up to date.

My problem is this. When I do a mirror synch, Toucan doesn't do a differential mirror - it seems to copy every file overwriting the destination directory. This wastes a lot of time.

Now, Toucan's backup mode has a differential function - but it zips the destination files by default. This is of no use to me because if the pendrive has zipped files, I can't really use my portable apps on the go without first unzipping and all the rest of it.

Is there some way by which I can differentially mirror my PC based portable apps with my pendrive without waiting for minutes on end even if only two and a half files have changed since the last synch?

Am i missing something simple here?

Many thanks for any help...