I think an account wide progression would be amazing, I really enjoy playing alts it keeps things fresh for me and ATM the pvp rank is really not alt friendly, they did it with CPs and I fully support them being account bound so why not alliance rank?
I wouldn't even mind if it was bound too one alliance so all my DC got the same rank and if I decided too reroll EP if have too start again, I can live with that, and if it was unbalanced in black water as some people suggest might be the case then I'd also happily support it being disabled in that campaign.
Making the system more alt friendly keeps players around longer when they'd normally have got bored and that can't be a bad thing