Contemplating getting a DDP for my VP9. Whats the real-world battery life? I know it has the shake awake, but does that really help?

The DPP on my Legion is coming up on 6 months on the original battery. Spends a lot of time in the safe but I take it out at least once a week. Seems to work well for me.

The one on my Staccato is going on 6 months and still going strong.  I don't worry about it much.  The batteries are cheap and very easy to change on the DPP.

Had one on my EDC, a month to two.

Not real world but I just had one last almost 2 years (AR15 pistol) sitting on a rack and only moved once every couple of months to be inspected, wiped off, lubed.  It did spend some time going to/coming from the range and some range time making sure it was a 100% reliable not long after I built it.

I did put a new battery in a couple weeks back when I had it out for it's latest check up.

On a CZ75 Compact carried almost daily (my wife's pistol for over a year) the batteries would last longer than 6 months (meaning I changed them out at 6 months and it was still working.)  I'm about to put that DPP on an M&P 1.0 9MM PC pistol.  It'll do fine.

My DPP sits on my CZ competition gun.  It’s shot or used in dry fire 5 days or so a week.  About every two years at a match it goes dead. 😁