I've had well over a hundred slr's from all era's and with all kinds of usage in my possessions and checked them all against a pretty high end Sekonic, nearly all where within one stop accurate which with the latitude of film is plenty good enough, of course there were a few off but in general they work fine.
Of course this is anecdotal evidence, but to me it seems that they are accurate enough.
And otherwise just get an old Weimar Lux, they can be found for next to nothing and most seem to work fine.