I've had many Sola lights. I initially liked the built in battery but each of them had limits and cons. I had the 600, (2) 800s and a 1200. The 1200 was my favorite. But each had eventually came up with corrosion at the charging contacts on the light head or problems with the cord on the charger itself. I had the battery go in one mid trip. That sucked!
My favorite dive light for focus over the years was the Fisheye Fix HG20DX. It was awesome with all the right features. It did not have a red bulb but it came with a red filter cap. The battery charging system worked well but if you lost the rubber grip that was included you could not open the light to install or remove the battery.
I've had the Kraken 1500+ WSR and it is fine but for a little more $ the upgrade to the Kraken LTD 2500 serves as a tremendous primary dive light, as well as a great video light and it is still small enough to use as a focus light. I do like that the Kraken 1500 & 2500 use the rechargeable 26650 Lithium Ion battery. Each comes standard with the Sea & Sea YS mount which is great because I rarely want my focus light to move side to side and it eliminates the need for 2 balls and a clamp which extends the focus light to high for me. I think Backscatter sells the Kraken LTD 2500 for $225. This is not the Kraken 2500 V2, which I am unfamiliar with. The batteries Kraken uses are indeed Weefine and they have a built in USB port so no additional charger is necessary, but advised.