Post the before pic, the change from the old is impressive.
Ok, Good Luck. I would have to see a 10 year example with great results before considering it. I might buy a plank for such an experiment, though. I didn't see any other reason to dislike it that I can remember.The old Trex was just particle board wrapped in plastic. The new Trex type of material is PVC and wood dust mixed together, so when you cut through it, all you see if plastic shreds and dust on the floor. I don't know if it includes a sunblock on the material, but would expect the sun to bleach it out in a few years. If and when this happens, I will just apply a light stain using a rag, and it should be good for another 5-10 years.
On your decking, I would test a patch with a stain to see if it blends correctly, and if so, would consider buying a Thompson sprayer, adding a gallon of spray, then wipe and smooth together using a rag wrapped around a push broom.