...help.
Thanks. This is actually what I was hoping to hear, because of the price.
I dont know for how long now you have been using your M2, or how often you dive, but if you do night dives and keep the light on, how often do you change the batteries then?
Ko, I've almost all my dive experience with this computer (over 100 dives), several of which are night dives (probably 10 to 15 I'd say).
In general, I've been able to do about 30 dives (aprox 25 day, 5 night) on a set of batteries without getting a low signal. If exclusively night diving, you could probably get away with 10 dives with the backlight on with a fresh set of batteries... If your batteries get too low during a night dive, the computer turns off the light (you can still access it by pressing a button), but the computer keeps on working. According to Mares, when the low battery light goes on, you have enough to still finnish your dive plus a few more dives. So no worries of your batteries dying on you during a dive.
Personally, I've always recharged the batteries way before getting low, so it's just basic maintenance.
Oh, by the way, I made a mistake before: it uses 2 AAA batteries!
The puck seems to do pretty much the same, without the AAA batteries and permanent backlight. Plus the button and navigation in the menu seem to be improved. But is this worth the price difference? That's up to you to decide!
Cheers!