But what can happen to the merged guilds/raid groups do if their is a discrepancy or if a player/players from group A wants to shift over to group B? Or possibly one group tries to steal one player for their own leaving the other group one player down and the other too full?
Their are so many possible things that can go wrong in these types of situations that can literally destroy just more than the guilds that have merged these players in the guild (Merged guilds) friends can turn on each other and friendships can be broken. I want to say you're thinking too much of this as a equation and leaving the social/emotional aspect of the game that has literally kept this game alive.
Along with the ranks and privileges given to the GMs/Raid leaders what if the owner of the level one alt that is the GM just decides he wants to knit-pick all the good players from all of the raids groups to make one amazing raid team and kick all the people he/she does not feel should be in the guild after that decision.
I'm not saying what you've done is wrong at all I am actually very happy to see people actually getting along and acting like adults rather than two competing guilds fighting tooth and nail for the players on the server for their own guild. I applaud you for doing this it must have taken great thought and many trials and errors to achieve what you have done with the guild merger(s).
From my own personal experience I have never seen a guild merger end well (Remember Annihilate? I was in that merger.) But you know their is always that 1% that just makes it through and everything would be fine.
And don't take anything I said offensively generally look at things more as an equation like I stated earlier in one of my previous paragraphs I generally don't add the emotional/human characteristics of things but sometimes I do. :)
Oh and Hooray For Evil will always be my home as long as they let me stay in!