I haven't had any personal experience with UK boxers but I did grow up in South Africa with boxers, and my family down there still has them today, and most of their lines stem from the UK and some from Europe. However, I don't believe that any of these dogs came from breeders that were breeding them for work/sport (Schutzhund).
From my experience I really haven't noticed any major differences. I have 3 boxers at home and all of them have differing personalities - some more closely aligned with the boxers that I grew up with, and some not.
I have met one boxer that had the most incredible drive and she was USA bred - but I would think that a lot of the breeder's (USA or Euro) who are breeding for work/sport are breeding dogs like this. Other than, in the USA I have seen many differing personalities - some very eager to please, some not, some with strong prey drive, some very distractable, others not so much, some laid back, some wild etc.
I know a boxer is a boxer, but I know the imports are geared (and bred) more for the "working" drive and just wondered if anyone noticed the difference ? or is it all a falacy?
I believe this to be true of some of the dogs coming from Europe (and even some bred here in the USA) but as far as I am aware the dogs coming from the UK are not bred specifically for working drive. Or am I wrong?