Chip tuning despite high mileage ??

Hello, dear people!

Actually, my 3.6-series has quite good driving performance as standard, especially when you think about the weight, the automatic and the friction resistance of the quattro.
But as always, there's never enough, and that's why a few more horses would be okay...
I've read a lot here and almost only good things about the Blue Diamond chip and guess that you can hardly invest 200 euros better.
However, my machine already has 285,000 km on the hump and even if it makes such a very good impression (no noticeable noises, oil consumption etc), I have a bit of a shot that the beautiful engine on its old years with the extra power could be overburdened and give up its mind early.
Was meint ihr dazu ?
Has any of you been chip-gunting a similar old engine and what experiences did he have with it?
Can you still count on the approximately 13 additional hp after the mileage or is the chip not worth it anymore?
Thank you already in advance and nice greeting !
Michael