I just got done reading your article, and I found it to be a good read. I discovered it by looking for an article that compares 500px vs Youpic.
Like you, I have several different photosharing accounts, like 500px, Flickr, instagram, Youpic, and so on. I originally found 500px to be intimidating and would never look past the opening page. After a year or so, after discovering 500px (it was bloatware on a tablet I won in a contest), I took a deeper dive in to it. I found that once you get past the “popular” page, there are a lot more unadvanced photographers. After that it became less intimidating.
All of that to say this: I do like that 500px gives a “score” to a photograph, and I use that as a tool to help better my photography skills. I feel that out of the sites, that one helps my photography the most.
I did belong to a great community on Google+ that was very close knit and everyone there encouraged everyone there. Unfortunately, the adminis decided to move that community to Facebook. Ugh!
Flicker… too confusing.
I have a love/hate relationship with Youpic. It seems the likes are in reverse. My best works get very few likes, but my selfie eating a bowl of Corn Flakes* gets 100 likes.
I think for the time being, 500px will be my go to photography site.
* I’ve never taken a selfie eating Corn Flakes