I have both in 5x4” format on two cameras.
When using the camera with the Bail back, I am quite happy with the ease I can insert the film holder. This camera though has a 360º revolving back which can be locked in any position from zero degrees to anywhere, therefore it is possible the camera back may be running at a very odd angle. Having a bail back in those conditions, is a definite asset. However it is still possible to move things slightly, one must always take care.
My bail back camera is a Toyo 45G monorail, essentially a studio type of camera, but one that I have taken out into the field. Also my previous Calumet monorail had a bail back, loved it.
My Shen Hao 4x5” wooden folder (HZX4x5-II) doesn’t have a bail back. As Brian Shaw suggests, one has to hold the camera, while at the same time pulling the back and pushing in the film holder. Not really an issue, however it is possible to move things ever so slightly easier than with a bail back.
I would suggest having a sturdy tripod with the ability to easily hold the weight of your camera, would be more beneficial in stopping movement that can occur when you load a film holder, over whether a Bail back is better or not over a Graflock back.
Probably the real reason camera movement is detected, or happens, is because things are not correctly tightened/locked before going ahead to insert the film holder. There are a squillion ways to destabilise a view camera, anyone who has used a view camera with film holders quickly understands this.
A Bail back is handy, that’s all.
Good luck with your endeavours, it should be a great ride.
Mick.