There were a couple of versions of the M. Mine is the earlier version, before the F was available, and takes the 6 volt 544 (4SR44) battery (a stack of four SR44/A76/357 button cells in a metal jacket). This version retains the film speed setting unless the battery is removed, and automatically turns off the LCD display about 2 minutes after the last button press. It has a measure lock switch where the later M has the on/off switch, and retains all settings properly when switched to the locked position. The later M uses a single AA cell, and I haven't used it or the F. Does anyone with instructions for the later M know whether the off switch is expected to be used routinely, or only for long term storage?
There was also a test in Camera & Darkroom (at least in one of its incarnations) that showed the Minolta to have significantly less flare than the other spotmeters at that time, including IIRC the Soligor and Pentax 1 degree spotmeters, which is important when metering a very small area.
Lee