I used to have the MK1XL but both the MK3 and MK1 have the same designs and fabric. I think Integral Designs makes nicer tents (I also have a Bibler I-tent, so I can compare them side by side). ID's tent has a thicker fabric, a tougher corner loop fabric. Setup is easier, too, just aim the pole to the corner and pop them up. As for Bibler, you gotta make sure to insert the pole tip into the metal buttons, which sometimes becomes a pain in the neck.
I also don't like the screen doors on the outside. It catches a lot of snow, but you can special order it with the screen door on the inside (that's one big plus for ID, you can have your tent customade according to your liking. Bibler does not offer that).
Hope it helps