RDP Thing 6: LinkedIN, ResearchGate and Professional Networks

Do you think these tools [LinkedIN and ResearchGate] offer a good way to present your professional profile, or do you prefer something else (a website, blog, etc.)?
If you use Facebook, do you feel that LinkedIn and ResearchGate are a suitable alternative space for professional activities, or do you find Facebook works just as well?

I have profiles on both linkedIN and ResearchGate (As of this time I don't have a profile on Academia.edu so I have skipped this other major network). I am a big fan of all social networks and these are no exception. View my linkedIN profile and you will come away with the impression I am a professional, focused and work driven individual, which is fantastic for my potential future employers to see. If sites like Facebook have caused us to create fake personas and lives to showcase to our friends, then linkedIN is exactly that, but for our future colleagues and employers. I don't believe it's some ruse or obfuscation of truth though, the site is just serving its intended purpose of presenting an online CV for the world to see. I do find it funny though to imagine the additional 'skills' and 'achievements' I could add to my university friends profiles; Skill: Can consume bottle of VK in under 5 seconds, Achievement: 80% of marks in Nuclear Astrophysics despite only 20% of lectures attended. 
Facebook works surprisingly well for certain professional activities, almost every time I was assigned a group project throughout my physics degree there would immediately be a Facebook 'Group' or chat created; to organise project meetings, to share questions or project information. I feel that group projects would have required far more hassle and work if the 'information sharing space' that Facebook provides had not been there. 
I think that both LinkedIN and ResearchGate achieve their purpose remarkably better than a professional blog would, as a a blog requires a constant updating of posts otherwise it seems dead or out of date, whereas LinkedIN can remain a testament of achievements throughout time and requires much less input. Research Gate requires very little input my profile appears to pretty much update itself; colleagues have added me on 3 publications in my bibliography that i have co-authored (some of which I actually forgot I worked on). 
I have yet to 'Collaborate' through ResearchGate even though such a feature is available through creation of a 'Project', where one can share their work, ask questions and communicate goals all on one page related to one grand project. The feature acts in the same way as the 'Group' feature in Facebook, that you may recall me saying I used throughout my degree, a Project is a message board where all 'collaborators' can post to. It seems that it will be very useful in the future and I am sure I will utilise it once I know what my project title actually is and I have some worthwhile work to share. The whole of ResearchGate maintains a professional scientific formality which I believe does prevent it being used by students, with many including myself opting to stick to Facebook for degree work. I have come to the conclusion though that this formality is absolutely needed to keep communities like research gate free of "trolls" and "internet experts" that populate the rest of the non-professional web-space, so I am happy with ResearchGate remaining the gated off community it is.