I think the forum/facebook comparison is pretty moot. This place has 5000+ members, their facebook pages has 3000+ likes. They're established and will probably get a higher ratio of likes to new members here from now on, they can conveniently control their page and get more casual people looking at it.
Complaints about ZFE are well tucked away now under various posts of 'your shop is crap'/'i love your shop' in posts by others so looking at their page you wouldn't even be aware of it.
Well the real
PR is in getting the glowing reviews, special pieces in mags or sites and getting the likes of Mark Kermode to pronounce it as glorious on the BBC.