My first Digisix also lasted less than a month on a battery. Swapped it under warranty; the replacement is certainly an improvement, but it's still not what I had hoped for. I'm guessing one battery now lasts between half a year and a year.
I came across a Gossen Prosix for one euro at a flea market. Put a 9V battery in it, and have been using it for a few years now. Sure, it's more bulky, but at least I can rely on it...
-- A sinister little midget with a bucket and a mop / Where the blood goes down the drain --
I have found, and others have anecdotally confirmed, that the 'gate time' (the duration of the actual reading of the light level) on the Digisix is so short that some light sources can be difficult to read. Fluorescent lights with a magnetic ballast and an AC line frequency of 50-60 Hz are actually switched on and off 50-60 times a second. The Digisix reading is so short that it can meter peak or minimum outputs varying by a couple of stops with these lamps. The higher speed electronic ballasts (15-20 kHz) are no problem.
Originally Posted by labcoat
If you have other PWM (pulse width modulated) light sources or a CRT that scans at less than about 85-90 Hz, you can also read only part of the cycle with the Digiflash. Holding down the reading button activates the differential reading mode, and will allow you to see the reading jumping up and down as the 'gate time' of the meter hits different parts of the light output cycle.
Minolta's Spot Meter M came with flush buttons that were sometimes accidentally pressed in the case. They ended up supplying a raised plastic surround piece that would self-adhere to the meter and prevent this. One could easily make something similar for the Digisix/Digiflash. If you keep seeing the 'out of range' display, "Eu", on the meter when you take it out of the bag or case, it's likely being activated accidentally.
Despite these oddities, the Digiflash matches my LunaProF perfectly across the entire range and is small enough that I always carry it. I also like the fact that the meter display holds the reading in use because I can always glance at the last reading before taking a new one, then only use the EV change to adjust the exposure from my last setting. That makes it faster in use than most other handheld meters. I always carry a spare battery.