I think the fact that flutes are loved by professional flutists is good evidence that they are good, but the fact that a flute isn’t played professionally is consistent with its being very good, too. Also worth keeping in mind that there are new makers are the market who haven’t yet been much discovered but who may well be making first-rate flutes.
Then why do you keep it? 
I think far more flutes (instruments in general really) are more than ‘good enough’ for most players than most would think . The fact that the world’s best players play such a varied and sometimes eccentric assortment and that designs have ranged so widely over the years bears that out. It’s important to find an instrument you like, of course. But I think too many people don’t spend enough time learning to like the instrument they have.
Ha .. just saw this now ..
Of course I meant ‘the Olwell has never failed to please’