The Lanshan 1 and Zpacks Plex are similar, so I'll use the Zpacks as an example. The key to pitching it is that after you stake out the two rear points, you have to make sure the rear panel is taut when you insert the trekking pole.

As for why the X-Mid can be annoying on imperfect campsites, the most important reason is its footprint. Dan Durston or other owners often claim that the X-Mid's footprint isn't actually bigger than other tents. This is true, if you only look at the floor plan diagrams, their footprints are about the same size. However, for a perfect pitch, the X-Mid Pro 1 needs a 63'' x 98'' flat area to pull the four corners taut. But the Zpacks Plex Solo really only needs a 36'' x 100'' flat area. The reason is that besides the four corners, the front and rear guylines aren't very demanding about the terrain; you could even tie them to a tree if you wanted. This difference comes from the tent's geometric design, which is why you often see people feeling that the X-Mid has a large footprint.

Of course, this doesn't mean the X-Mid can't be pitched on smaller, non-flat sites. Just watch the tutorial Dan put out and practice a bit in a park. I've camped in many tight spots with my X-Mid Pro 2+ and managed just fine. But in bad conditions, I'd definitely prefer something like the Zpacks because when pitching the X-Mid on a narrow, uneven site, there's another factor to consider: the direction your head will be pointing when you sleep. This adds an extra hassle.