I’ve spent the last 25 yrs racing (only 30 now) first experience was racing the family 32′ cruiser racer. Move to dinghies at about 12 mostly racing ents with a mate, then into 420 then 470 then fireball and finishing recently in B14’s occasionally.
At the start I did quite a bit in a topper racing but we used to laugh at Oppie kids. Quickly moving to lasers.
I remember the kids winning everything always had good gear. Sorry but old boats are heavy, things break and cost you races. Sails will be great on new boats and top kids will have new ones often. Old sail will be baggy and that creates drag.
the answer is a new boat will probably keep him enthused and hence competitive breeds enthusiasm. Loads of my mates haven’t sailed for years and fell out of it. I never had great gear but generally good stuff and went on to do lots Inc win a euro champs and delivery trips to Gran canaria before being 25.
Whatever you choose he won’t be there long and will be in toppers soon.