Too many pacts is without doubt a negative.
First off, if you go around pacting the entire server, you have no targets to conquer, thus it's going to be pretty boring - you will most likely have a lot of aggitated players sitting in these alliances, which can only result in people either leaving and starting an alliance for their own, or people violating the pact terms.
Secondly, I doubt the alliances that are pacted now have any idea of what the other alliance is capable of; will they have to help them out with every single thing, or are they the best around on the server? You can't tell this early in the game.
You should only pact another alliance when it's absolutely necessary for the prosperity of both alliances; I'd recommend one, maybe two. Anything more than that will be detrimental in the long run.