Do bantams integrate into standard sized flocks well?
Bantams and standards can work fine.
Many bantams have traits that could be problem when free ranging:
crests (block vision)
muff/beard (big ones block vision)
feathered feet (long feathers make it hard to walk or run; little feathers are fine)
short legs (make it harder to walk or run: these are found on Japanese Bantams)
strange feathers (Silkies and Frizzles get cold and wet more easily, and cannot fly)
If you choose bantams that just look like chickens, they will probably do well enough ranging with your standards.
Because they are smaller, bantams are easier for a predator to grab. But because they are smaller, bantams are more likely to actually fly. So whether they survive better or worse will depend on what predators are trying to catch them, and on how the individual bantams act.
Broodiness varies from one hen to another, but bantams do tend to go broody at a higher rate than most standard-sized breeds. So you might want to think about that before getting them (broodiness can be good or bad depending on what goals you have for your flock.)
