The projected image made by my old (ca.1972) DGA dichro colourhead of my Beseler 23CII is also quite dim. A lot of its 300W halogen's power is lost in the colour mixing head and its dichro filters. The later generation of colourheads must be more efficient since they use 100-150W halogen lamps to do the same purpose.
Even with dichro filters shifted out of position for focusing, the projected image seems to be much dimmer than if the same image was beamed through a 75W opal lamp in a condenser head.
Have you tried using the Russian colour enlargers? I have an old "TЕХНОИНТОРГ" catalogue from 1985 which listed a Russian colour enlarger, the "ДОН-103". I always wondered how it worked- it looked like it was based on a similar looking Leitz Focomat. It had automatic focusing and had a craned head.
Also, the Russian enlarger lenses are quite wonderful to use. The "Вега-11У (2,8/50)" is built like a well-made German or Japanese lens and probably costs only a fifth of what a used Nikkor EL 2,8/50 would cost. The "Индустар" enlarger lenses, like the camera lenses they were based on, are quite superb. The last lens I used before I stopped making "wet" darkroom prints 3 years ago was the "Индустар-96У-1". I used it almost exclusively for making colour prints on RA-4 paper. It did better than a Nikkor-EL 4/50 that I borrowed. Got all the lenses cheap- the
Vega was only US$5 from eBay, and the Industars (three of them) were all given free by friendly Russian and Ukrainian sellers there.
The И-96Y at least had a removable barrel which allowed me to use it on the Beseler fully. The other Russian enlarger lenses had long barrels which limited the bellows' movement and allowed it only to focus for prints up to postcard size. These lenses had to be used with recessed boards for more flexibility.