I have a small porch/deck that is at least 30 years old. Except for some slight fading that happened the first 3 or 4 years it is the same as when I built it. It has a totally unshaded eastern exposure. The only problem I have with it is that it can get slippery when there is snow on it.

One thing I had to plan in when I built mine is that the deck planks aren't as stiff a comparable redwood. They recommended a closer spacing on the joists supporting the decking. I did that on mine and have had no sagging. That was thirty years ago so I don't know if the current decking is any stiffer. This would be something to check on if all you're replacing is the decking.