I have heard hand individual strength mentioned in this thread, but not that the effects of differing amount of it may be mitigated by the brake adjustment. Having fairly large and strong hands for a little guy I always keep the shoes quite close to the rim. This means that more strength is required for the brakes, however. If one adjusts them a bit further off, the time for the shoes tocontact the rim is only minimally increased and you are in the range where less hand strength is required to firmly engage the rim. When I read of brakes tests, I always wonder if they are set up identically for the tests or if they are just tried on different bikes.
Truth is, I find nearly all vintage brakes adequate when set up well (a couple of notable exception do exist.mostly the more exotic looking ones) and that some brakes (cantilevers, for instance) can work almost too well. Caution must be taken in panic stops with them and judgement and experience may be necessary before the risk of an accident due to over braking can be ruled out. Nearly all of them are capable of putting you over the bars under some circumstances.
In short, if your vintage brakes are not stopping you the way you'd like, try some adjustment (or different shoes) before you give up on them. A