Cobb and Martin co-authored a chapterin the book “High Performance Cycling”. They claim that a disc is about fourteen seconds faster over 40 kms than a good aero wheel.
Is there a athletic level or average speed that would warrant the upgrade?
It’s all in how YOU can justify the expense. It has nothing to do with speed or ability. If you’re worried about what other people are thinking, then that’s a self-image issue, not a performance issue.