I have to say, I agree with RichG: I have a number of Sennheiser wired and wireless 835 microphones, and when I try to put my Line 6 D75 into the mix, whether on the 835 model or not, the feedback begins. It is by far the least stable wireless I have ever owned. That combined with the frequent dropouts, makes it a beautiful paperweight in my rig.
I was a HUGE proponent of the X2 systems, and still own several of them. However, I cannot say the same for the stability of the Line 6 versions. The sound quality is excellent... But if it's dropping out because it's being used in a room full of cell phones or whatever, that's death in the sound business.
