I rebuilt a deck last year. I had some Trex boards in certain places on my deck when I started the project. They had been on there for about 5 years. When I started the demolition process, the pressure treated boards held up very well when I used a demolition pry bar to pull up the 11 year old planks. The 5 year old Trex boards I installed 5 years prior as a test, not so good. They were brittle and would easily break if I had to put the pry bar under the faux board because of a stripped screw or whatever. They were also very faded and looked worse than the 11 year old planks that had never been stained, sealed, or pressure washed.
I don't have pics to post yet, but I just applied some Cabot Australian Timber Oil to my deck. It is the natural tint which basically results in your deck looking like wet boards when it isn't raining. It is a mix of tung oil, linseed oil, and alkyd. Basically a preservative oil that soaks into the wood instead of sealing it. Very good stuff and easy to apply. The natural tint has good UV protection as well while enhancing, not hiding, the woodgrain. Just thought I'd throw this out there in case it could help.