Van Persie is an exception for me due to his brilliant technical and mental stat's which haven't declined all that much since the start of the game so he's still a great player to stick up top. Plus he makes a brilliant tutor too!I can see the point of keeping RVP till hes 33/34 but I always sell people by the time they become 31/2 ...
I tend to sell people by the time they're around 29-32 in order to get decent fees (unless I really like them), regardless of the club situation, but RvP definitely is an exception to that rule. He is definitely worth the salary paid to him ingame (shame I can't say the same IRL atm). In my save on the default database, he got around 40+ goals each season in the League until he was 35 or so, after which I got bored with the save. I dunno how he'll progress in the latest database, but atm, in the first season, he has 33 goals and 5 assists in 16 matches.
Thing with RvP is insane technicals and mentals which totally make up for average physicals. Those insane stats, coupled with 'Shoots with Power' make him an unstoppable goal machine.
Precisely why I tend to keep him plus he's a brilliant tutor and captain too!