Really good point here and probably directly relates to the number of players participating in GvG. While you say the code is "complicated" (and no doubt it is) a very easy fix to raise the participation rate would be to have 2 resets per day. That way you'd have players from different time zones participating, and you'd also likely have more movement on the maps - not just the same handful of guilds dominating each age.I agree to this proporsition - Guild Battlegrounds. But when you are developing this feature, I'd like to suggest to keep in mind, that Guild Expedition is popular, because it doesn't require all or many members to be online at the same time. GvG, in contrary, requires to be online many players at once. And in reality it's difficult to get many players online, especially in such cases when players in a guild are from different citie, countries, etc. So if game developers are able to figure out how to improve Guild Battlegrounds by allowing members NOT to be online at the same time, then it would be huge success.
If GvG is a done deal and no improvements are going to be considered, then I'll have to reserve judgement on Guild Battlegrounds until I'm able to play it. Sounds like an interesting concept.
Attrition - sounds like a way of penalizing players that are fighting focused - our guild has learned to balance our membership and have fighters as well as farmers, with this attrition system in theory it sounds like you're trying to level the playing field but in practice what's going to happen is you're just going to limit the amount of fights the fighters can have and the farmers are still going to farm with no interest in fighting.
It also sounds like you'll end up matching the same guilds over and over which will get boring - with the current system of GvG any guild can participate and most of the time it's the smaller guilds that cause the bigger problems. The new version sounds like being in a smaller guild will be a distinct disadvantage/