just to be this old tread into context, my guild in EN1 now gets 8840 support pool and most of that is from GvG, so we can pass 50% defence across many sectors.
but as players have leveled out attacking GB's the support pool became less usefull and now when fighting a 75% HQ does kill an extra troop or two and a 50% either 1 more or more damage - but it does not really stop any attack now