Wireless flashes - worth buying, and which?

Hi,

I'm thinking of investing in wireless flash for my epl1 Olympus camera. It appears I have two options, the SL50R or the SL36R. I know very little about using off camera flash but want to learn. Comments welcomed on the following:
How these flashes compare on performance?
Are they worth buying at all?
An limitations on either that is worth knowing about?

Thanks

Laura