In truth, the big problem with the X-Men is that they're really not suited to be in the Marvel Universe. The Marvel Universe was a proto-Bronze universe from the beginning (or at least Stan Lee's kicking off what we know now as the Marvel Universe). The concept of the X-Men came from a science fiction book, or a couple of them.
Most superhero teams are ultimately about preserving the status quo from various threats. The X-Men are one of the exceptions. They were all about changing the status quo for the better, and built into their fundamental concept was the idea of the human race changing and evolving into a higher species, homo sapiens superior, mutants.
The problem with the X-Men is that the Marvel Universe to some extent remains a status quo universe, somewhat different than our own in some areas but ultimately familiar to everyone. All of the fantastic technology that Reed Richards and Tony Stark invents never fundamentally changes the world at all. For all that people of Earth know about alien worlds and other dimensions nothing ever really happens because of it.
As a result, the X-Men who are all about dealing with change and evolution and so on, are stuck in a universe that doesn't fundamentally allow it. They're stuck with nothing ever improving, nothing ever changing, for better or for worse. The threat of a serious mutant pogrom can't happen, because it would screw up the rest of the universe and they can't really make any progress anywhere because again it would sort of screw things up. Only in alternate timelines is anything interesting allowed to happen. The X-Men really belong in their own universe which is allowed to deviate significantly from our own universe due to the existance of the x-factor, and where more or less all superpowers derive from the x-factor gene complex.
And frankly I don't see the infighting in the X-Men as being all that much worse than what goes on in the Avengers. From what happened to Pym to what happened to the Scarlett Witch and the Vision, to what is going on now in the Avengers, I think they've lost a lot of their heroic advantage. The main advantage is the Avengers tend not to angst, though Spiderman is the past grandmaster of angst.
And if y'all are wondering WHY i haven't been posting much, here it is:
It is about the upcoming cover, in progress, for Pitch Black's "Razor-Edged Arcanum". Now called Sages & Swords, name change while I was working on the piece. An short story anthology of wizards, magic and such.
If you are curious to see the process, I will repeat the link:
http://forum.rpg.net/showthread.php?t=192472
Enamel reacted to Mutant for Hire in I could watch him get slapped around all day