we had two, that were to go in with our 2 (had from POL).
they took a long time to adjust.
We were told that if we put them in at night, they would be okay, but we eneded up having to build them their own coop and separate it from the rest of the run.
they basically had a run within a run for weeks.
To make it worse, they couldn't even be in with each other, so we had to make a partition of wire in that coop and run, so that they couldn't peck each other to death.
we had to rig up 2 sets of food and drink bowls.
We had huge problems when we let them out into the garden, and had to have them in a chicken wire run, split in two down the middle so they could see but not peck each other.
yes, it was tough for months, but eventually, they got used to it, and they were great with humans.
Rita, especially , was very cuddly.
I'm not trying to put you off, by the way, jsut outlining how hard it can be to integrate them.
I would definitely take ex-batts again, because the rewards far outweigh the inconvenience.