I have recently started reading Uncanny X-Men for the first time, largely because of Salvatorre Larocca being the artist (yes I'm a big fan especially his run on Star Wars). I was surprised by the appearance of Captain America in issue 11. I was under the impression that the X-Men were in a different universe to the Avengers universe, hAs this always been the case?
Personally I think it would be better if the Uncanny X-Men existed in a different universe as there appears to be too many heroes in the Marvel-verse. It also begs the question whether the non-X Men heroes of the Marvel-verse posses the mutant gene of the characters like Spider-Man, The Hulk etc had the mutant gene which was activated by their related triggers e.g. The spider bite and gamma radiation explosion.
I would live to hear others thoughts.