All I can say is I've had mine for 3 weeks and have primed approx. 500 cases. After the first 60, I reread the instructions and the next 100 went smoothly, all 100 non-stop. Wrong side, right side, nerf launcher? Mebbe. But I have run military surplus rifle brass, commercial rifle brass, mil surplus pistol brass, commercial pistol brass, revolver brass, any headstamp and when I follow directions I can dump 100 primers in the "backwards" tray and stuff primers until the tray is empty...
I haven't seen any thing that stands out, pro or con, about the new foldable primer tray as mine has worked just fine.
I don't find the position of the shell holder odd or uncomfortable. I have the tool in front of me with the handle/tray on the right side (A pause for the COZ's pics show his tool mounted fore and aft, where I mounted mine left and right). I pick up a case in my left hand, insert it in the shell holder. With my right hand I actuate the handle, feel the primer hit bottom, and move the handle back, making sure it fully travels to the stop. Remove the case with my left hand, drop it in a tray and get a new one.