Valves are millage so they are fine. Belts are age and/or miles. recommended is 2 years, many leave it longer though. I'd replace if it was me. Under £100 if you do yourself.
I first fitted kevlar reinforced belts to my car back in 1999...I would guess by 2017 all the good branded belts are kevlar reinforced? I might remove the covers and check in the weekend. Am I right in assuming (based on your lines) that there aren't kevlar reinforced belts for 998?
Never heard of this brand but seems a lot of positive feedback on this site..I was all the time using Continental Kevlar reinforced belts in my road and rally cars.
Correct - Ducati Belts do not have Kevlar in them, although I have seen Ducati Dealers advertising Kevlar is in the Belts. Ours too have different fibre reinforcement as Kevlar would not be ideal for this application.