I think it is highly unlikely that merges would ever be based on a players global ranking (score) as this does not reflect where you are in the game at all, you can have a player will 200k points at the same stage of the game as a player with say 50k points. The more active you are as a player, the more fighting you do and win, the more you collect and build and so on takes your score up.
For the most part merging does work well with the new system, but there are still odd players who do find them selves in a hood they perhaps shouldn't, but in the majority cases this rectifies itself at the next merge.
In the event any player ends up in a hood which you feel is really imbalanced, while we may not be able to manually remove you we are happy to receive tickets to make us aware, as if this was to become a common issue, the merging system may need to be reviewed, but at the moment for the most part, it does seem to work well. Kim.