Girlfriend and I were up at PVG last weekend. I saw the PRC eChannels and remember a TVB Shanghai Expo segment saying HKers with home re-entry permits registered in Guangdong checkpoints can use the same at PVG. I was snorting "Hmmph! Let's see. Bet it's a load of BS this thing is national (not just Guangdong). Bet you we'll have to walk back to the Chinese nationals line". I lost the bet seconds later.

I was a bit surprised I couldn't do eChannel on the outbound. Whilst not ubiquitous for PRC eChannel border controls e.g. Huanggang also doesn't have it, some do (I recall Gongbei does. But my re-entry permit didn't work there).