Alot of it comes down to the preperation work. I've had mine done for 2 years now and it still looks great. I can only speak for mine but it hasnt faded, it cleans with a quick wipe with a sponge, or even just a damp chammois, and as its only a coating on the outside, I cant see any reason it would have any affect on performance....its not a mechanical item.
I do however also have chrome items on my Calibra engine bay which has been off the road for quite some time lately and as a result, damp has caused the chrome to start flaking. After using the Skyline so regularly, it hasnt had a chance to start doing this but that again could be down to the quality of work - the Skyline stuff stuff was done at a different place and I paid more for it.
Here's a pic of my engine bay...I think you might be tempted
My engine and ancillaires have been chromed,,, almost identical to phils. Again mine was good quality chroming, 3 stage processs something like copper then nickle then chrome (not sure of the actual metals) and it has lasted and still going strong 3 years later. Quick clean now and again with polish thats it. Polished stuff is ok to start with but weathers after a bit and cant get back to the shinyness of the chrome