I have printed with the W55, W45, the VC8100, and now the V54. The V54 is the winner here. It is, by far, the brightest of all of these. Printing 5x7 onto 8x10 paper with exposures in the f/22 - 32 at about 10sec on Bergger VC CB. This is at least 3 stops faster than the VC head. It is kind of nice to just turn the knob for a contrast change, but exposures are long, hard to see, and the unit is very expensive.
The W45 doesn't offer a very good distribution of contrast, even with the yellow filter and although fairly bright, still not as bright as the V54.
The final straw here is that all coldlights require some kind of closed loop timer or stabilizer. The 'thermo' or heater in the head helps, but is not good enough to provide consistant exposures. Light output of the coldlight tubes is dependent partially on tube temperature. In fact, it is possible in some cases to have part of the tube getting brighter, as another part of the tube gets dimmer.
Given this and other variables, the dual grid VC heads cannot be controlled as well as the single (V54) heads, because the dual grids have two lamps on at the same time. If they are used in the split printing mode, then a controller will work, but not otherwise.
If you are going for a coldlight, get the V54. With a controller, I use a Metrolux 2, exposures are consistant to better than 1%, with or without the thermo even on.