I have remembered what the crucial difference is.
You load the film in the dark without a cassette which eases the friction so that the wind on spool can take the weight of pulling the film through.
Obviously this makes for more hassle but not as much as finding someone to manually perforate your films.
HOWEVER, I have been loading and winding an unperforated film through both my FM2 and Canon AE-1 and one in five times the film gets stuck halfway through.
The problem is that the leverage from the manual wind on device goes primarily to the sprocket spool rather than the wind on spool. I tried taping the end of the film to the sprocket spool and this would work if there was sufficient room around it to take the film.
I can't believe that this is an insurmountable problem and I'm going to have a chat with camera mechanic I know. I think the answer is to somehow cement the wind on spool to it's shaft to give you greater leverage or maybe even replace the wind on spool with a different one.
I will report back.