I have never had an issue with the battery life either, a battery will last approximately 1 - 1 1/2 dives and that is with about 100-200 photos with flash per dive this is even with a non OEM battery. I do not do much video so I can not comment for this. I completely agree With Deep Water Dan and the sync cables and possible water intrusion, any extra port increase the chances of this. I have only hear of a few cases but that was mostly due to poor housing maintenance, and I have seen a few flooded sync cords from diver error and connecting these cables.
I also now consider the ability to acquire things such as batteries and sync cables in different areas around the globe when purchasing a strobe. I used to have Ikelite 161's, very nice (except the weight and size) but one morning I was a bit too excited to get in on a dive and as we started to descend I noticed a brown liquid around my strobe, turns out I forgot to install the battery O-ring. The strobe was OK as it is sealed separately but the battery was flooded, I was unable to locate one in Bali and the person who had one in Jakarta wanted 500 USD which is just over 1/2 the cost of a new strobe head. I now switched to Inon as they are much smaller and lighter, their build quality, and as you only need AA batteries (this was not the only reason as many others use the same). Also with fiber optic cables you can make your own cables yourself along with custom lengths to fit what you need, if there is an issue it can be easier to determine and potentially repair.
Back to the G-16 The macro without the diopter is very good but add a diopter and you can get some nice close ups. I cannot find my non diopter shots right now but here are a few with Inon +7 diopter.
The last 4 images are the ones that uploaded correctly.