I wouldn't get stressed about old versus new first. Even for a regular F traveller the benefit is really only the bigger screen so if this is your first long-haul J/F then it won't make any difference at all.

Compared to travel in Y, you'll have a comfortable seat / bed, superior food / drink, lounges, fast-track and (most likely) great crews.

The only negative will be next time you're sitting in Y knowing what you're missing out on!