Go to B&H and look at the specs for Visatec, then go to
http://www.paulcbuff.com and look at Einstein specs. (Click all the links . . . there is a huge amount of tech info there.) In my opinion, Visatecs are among the most underperforming and overpriced monolights on the market. Slow flash durations, small control range, oversize, etc.
As for color vs power setting the follow the same curve as AB. WL, Elinchrom and just about everything else except Einstein, Bron Grafit style packs and Photogenic Solaire. Odd that Broncolor makes the most advanced high end packs and among the worst monolights.