Hi Netdoc,
If you want a lightweight, hands free super bright light I suggest that you try, if you can, the Watershot 1800 lumen dive light. It has a very compact 8 cell L-ION battery in a case that fits on your BC strap via velcro straps, and a coiled cord that goes to the light unit, which goes on your hand with a soft mount just like the one for the sola, except the light unit is smaller than the sola. Totally hands free and you barely know you have it on.
The battery pack will give you about 3 hours on high (1800 lumen which I use for bright daytime diving, bright enough to signal your buddy) and 8 hours on low (about 900 lumen, which is the setting I use for night dives). The beam has a bright hot spot of 10 degrees and great fill area of about 60 degrees; it combines the best of the sola spot and flood features, but at the same time and substantially brighter. Although it has the separate battery and light connected by a cord, I won't call it a "can light" because it is only a tiny fraction of their size, weight and bulk. Best of all the light control is on the head, a simple push button for on/off and to cycle through the brightness levels. Quality is very high and they relly stand behind their products. Going on two years and no problems whatsoever.
I have no affiliation with them except to give them my hard earned $$$, but it was worth every penny.
Also love solas, just bought 2 of the 4000s for video and they are amazing with huge batteries and long battery life. But, for a primary dive light, which I use on every dive day or night, the non-interchangeable batteries just do not work for me.