My experience with aging champagne is that it goes quite well with champagnes with at least 4g dosage. Non dosé doesn’t age as beautiful IMO and easily gets oxidative (which can add additional complexity but only if it meant to be). 5 years for a zero dosage has not been successfull to me (tried with at least 6 different grower champagnes like Diebolt BdB etc)
I have a Pol Roger sitting in my dad’s basement refrigerator that has been there for about 10 years now - I really should see how that’s doing…