I actually do this often. I have a 7D and the custom user setting for C1 on the dial is set to small jpeg for use when I'm doing "brenizer" type stitch shots. I carry my camera on a sling strap and several times now I've been on a portrait shoot and discovered after several shots that at some point, the camera had bounced on my leg and rotatedthe dial to C1 and all I have are small jpegs of the shots I did! So then I have to go back and reshoot the shots in full res raw. ERGH! I have considered sending the camera in for the locking dial modification that Canon offers for $100 but I keep expecting the 7D2 to come out and want to see if I'm going to upgrade or not first.