if that then applied account wide

As far as making it account wide, I'm not a designer, but that definitely hinders, again, the guild participation factor. Once you have guild rep set on one character, and if that then applied account wide, your desire to contribute to guild content that isn't pushing gearing your character drops substantially. However, if you have an euwowgold.com alt that's 80, yeah you probably will want to join in on that Blackrock Caverns run being put together. Otherwise you're a jaded 85 guildie who has variable interest in actually helping someone else out (Yes, yes, I'm sure you're the most selfless and helpful person in your guild, but that scenario is too often the rule and not the exception). It could also be gamed to some degree... but I'm not sure to what effect.

As I said initially this can be a weird start conceptually, but while contributing with guild members you're gaining rep, and you'll get access to those rewards from then on. As this is still a fairly new and fairly big and complex system we're watching it very closely, and fully intend to keep adding to it and improving upon it. Your constructive feedback is welcome.