There isn't anything wrong with buying that cooker, over making a UDS.
That door is going to be a potential issue, if it becomes one, a quick fix, is to wrap the door with a few layers of aluminum foil, that will seal things up a bit. Same is possible for the bottom joint between the barrel section and the bottom plate, drip a little oil into that and it will seal enough.
I'm feeling bearish, and I'm packing a Wusthof Grand Brisket slicer from MABA
"I'm Armenian...perhaps...but then again...maybe not..."