I use a side pull on the young guy I ride. We haven’t started using a bit with him and he seems happy and responsive with the side pull.
(not exactly, but almost like this)
https://www.statelinetack.com/products/tabelo-v-brow-sidepull-brown?variant=43799360438409&&srccode=GPSLT&gad_source=1&gad_campaignid=22158977702&gbraid=0AAAAADou2UwQZ1pfI6wB3DJb5N33ZtLCb&gclid=Cj0KCQjwu7TCBhCYARIsAM_S3NheSRuv3_JLpgXWC1eZ_K44OzZrxKRYinBsAP3qN3DbLxkRvtSEOt4aAo8fEALw_wcB
My friend has a Dr. Cook and her older gelding was always fine in it. The young guy didn’t go quite as well in it, though he wasn’t bad. Her mare is ok in it but seems more content with a regular bit bridle. We do have some issues with the nylon ones not sliding as well, so the release isn’t great.
My lady seemed very confused and annoyed. I think the cross under makes it feel somewhat like they are being pulled from the oppposite side and she’s like “why do your leg/seat aids say left but rein says right? Woman, get your act together!”