If you're staying stock, never off-road, or are not hard on the truck...I would call an upgraded valve a maintenance item if anything. I'm already concerned enough with all the plastic on modern engines...If I could eliminate as much of it as possible I will. I'm already running an upgraded intercooler and valve, switched to silicone joints wherever possible, and am using constant tension clamps over the factory items.
A lot of people like the sound, but I get not everyone does. The only other benefit I would say is worthwhile besides the added responsiveness and durability is the fact that valve vents to atmosphere. For those of you who don't know, the factory Crankcase ventilation system in these cars vents engine blow-by back through the intake system (This is essentially oil vapors and moisture back through the intercooler and back into your turbos...yay emissions devices).
My observations are this...in humid climates moisture is a big issue in these intercoolers, and I think Ford actually admits to knowing/observing this too because, on a lot of EcoBoost vehicles, the intercoolers have block off tape to bring intercooler temperatures UP...therefore reducing moisture in the intercooler by making it less efficient (warmer)...some aftermarket intercoolers even have drain plugs because it can be a lot. Before I had a blow-off valve I would have to empty my catch can EVERY oil change. Now with running a valve for the past year on my own truck, little to nothing comes out of my catch can anymore and oil build up in the charge pipes is greatly reduced...nearly eliminated. Over the long run, that translates to less oil gunk in the intercooler and in the turbos...not to mention the valve itself would probably outlast the engine compared to the factory unit.
As far as off-road debris and water...I've never had an issue
The valve location on these trucks is tucked away pretty good and since it only opens a few millimeters with heavy air pressure coming out I can't imagine anything getting in there....obviously don't go fording a river and revving your truck while you have water up to the doors (at which point I'm sure you'll be facing much bigger problems anyhow). You would want to stay on the throttle in that scenario as it is to keep water out of the exhaust system too.
Hope this helps.