Do not expect job offers coming to you if you are only registered on this (or any) site. Only an active approach on multiple sites might draw the attention of head-hunters. Instead of waiting, sending out applications on these sites a more effective approach. Your chances may even increase if you can make use of your professional network (like LinkedIn etc...)
In my opinion almost all large companies are using intermediate companies to do the (high level) personnel selection for them. So to be visible for them it might be useful to register directly at their websites and use key-words in your profile that draw attention. Key words like SAP, ABAP, Developer, .NET, etc. makes your CV appear on top.
But even then you have to pay attention. I noticed quite a few offers on my profile to be fraud, meant to let you pay for non-existent services or to use your CV for identity fraud.
