There's a book on mixed member proportional systems called The Best of Both Worlds?. What the authors found is that basically there were some countries with PR systems who wanted that element of local representation and had moved in the direction of MMP. New Zealand is probably the textbook case of this. It came from a very similar system to ours, but wanted that element of proportionality. Of the options out there, it probably is the best at melding those together.
On the broader question about social media and how that fits in, I have a whole other pile of research I can show you, which would take more than five minutes.