Actually, no. I don't consider $1200 flashlights as ditchable weight.Diver0001:I suppose this assumes that the can-light is seen as dumpable weight. There are certainly ways to combine them if neither the can-light nor the pocket is the size of a Volkswagen Beetle.
In a DIR context there may only be one way to do this but that way is debatable in other contexts given the advent of more energy efficient light-heads.
The issue is whether I need a Helios 9 18 watt HID on Bonaire, for example, where it resembles a runaway nuclear reactor above my fist in water with some 200' lateral visibility. I could signal passing aircraft.
For tropical night dives I suspect I could survive the dive using a smaller light, and stick a pouch on my right waist to run the long hose beneath.
However, if you want to take a can light to the tropics, have fun!
Doc