I discovered a design fault with the New Canon F1 yesterday that although i've been using them for more than 25 years, I recently bought a Canon AE motor drive FN so I could get shutter priority AE in addition to the aperture priority AE that the AE prism gives, and I have three of these F1N-AE bodys so I thought since you can't remove the motor drive with a film in the camera without exposing it because the film chamber cover screw has to be removed from the camera base to fit the drive, so I thought I could leave the drive permanently on one body which would solve the problem, but I discovered that if the camera battery fails with the drive attached to the camera it isn't possible to remove it and although even if the battery fails you get a full fill range of mechanical shutter speeds from 1/90th sec to 1/2000 sec. you need to be able to remove the battery from the camera first before the camera can do this which is impossible with the f***ing motor drive attached.
So I discovered this issue as well. I have a black film changing bag with me most of the time. If my camera battery dies in the middle of a roll of film, I take the MD off in the film bag, change the battery, and put the MD back on in the film bag. A little bit of an inconvenience but it reminds me to carry fresh batteries and check the battery before loading a new roll. Having said all that, I've only had a battery die, in the field, once.