50% buffs are indeed to much. I wouldn't take them out totally, but maybe lower it to 15/30 percent buffs instead.
And I know this one is against your vision: but no duplicate cards in defense teams
Also: If you are going to do something with defense teams, then please make them separate teams from your normal team list. For example: Have special separate color defense teams (Like Red Defense, Blue Defense) you can set. Because even with the added slots, it's not enough slots (unless you add some GW unrelated options to the troops page, like the favorite tag for troops for example).
I don't mind playing every week, but 6 days is a bit much. I would prefer 4 or 5 days.
Only the results of the top 25 or 27 members should count, as there is still quite a lot of player shuffling going on (due to people leaving/taking breaks). This would not hurt a guild if a few members are on holiday.
You should be able to level all sentinels up one rank at once, or maybe a few ranks at once.
Having to do them all one by one is quite cumbersome.
To me, the problem with Guild Wars is that it changes a do what/whatever you want relaxed kinda game, into a hardcore must play every day for an hour very intensely kinda game. Aka, the total opposite.
And where I was playing for fun before, I now play because I have to, and then log and don't come back until I have to again.
So less days, and probable once every other week would be welcome additions.