Well, I hear complaints all the time that people can't play their concertina standing - ordinary Anglos as well as larger Duets or Englishes - because they are too "heavy" for them. The question also comes up now and then whether it might be beneficial trying to improve finger "strength" by systematic training.
Concerning Anglos there is much concern about "weight" when comparing qualities of makes and models while the actual difference may be as small as 1200 and 1300grams.