True, poly motor mounts are a problem besides being stiffer and taking a set. Most serious is the fact that if the car is used hard (such as simply driving on the autobahn, or track events, poly motor mounts will MELT from header heat! This is particularly bad on the left side, as molten poly will run down and cover the joint between the upper and lower aluminum mounts.
On the right side, the entire mount assembly can be removed as one piece, but on the left, the gearshift rod goes thru a recess between the upper & lower mounts. So the two halves MUST be separated to remove them from the car. Unless you have a big hunting knife or preferably a chisel and hammer at hand, the left mount cannot otherwise be removed. Here, poly was NOT an upgrade except for gently driven show cars.