fighting Taliban in Iraq or Afghanistan will help PLA better prepared for the challenges from their real enemy in the future though. As we could imagine, the PLA's opponents will attack PLA from the water or the air, not from the caves.
I am not too concerned about PLA's combat experience. The Chinese army will gather combat experience when they are forced into a war. The general's capability to plan & to adjust is the deciding factor in battles.
Let me take Soviet Union's Red Army in WW2 as an example. The Red Army coordinated the German army to defeat the Polish army during invastion of Poland in 1939 but this battle experience did not improve the Russian performance in Winter War 2 months later. Though the Russians had superiority in both weaponry and men, Red Army fought poorly against inexperienced Finnish soldiers. The lessons the Russians learned did not prevent the Red Army from collapsing in the early stage of the Russo-German War in 1941 either.