White Lightning is built like a tank. Between the x1600 and the Einstein, I don't know which way you should go. The Einstein has the fast flash duration and constant color mode, something you'll never make the x1600 be able to do. If you shoot fast action then your decision is made right there.
Their max output is about the same, WL is just a hair more powerful. Einstein wins on the minimum output but there are things you can do to with the WL to get less light, like flag your light or even shoot with a polarizer or ND filter either on the lens or on the light itself......or just use the modeling light.
The WL has a 5 year warranty vs the 2 year on the Einstein which was my deciding factor when I purchased my lights, well that and the tough housing of the WL.
Call me old school, but I didn't care for the all digital controls of the Einstein. Sometimes I have to hire assistants that have no photography background at all, and for me it was a lot easier to teach them to move a slider. Stupid reason, I know.....but it works for me. I've thought about investing in the Cyber Commander so I don't need someone to adjust power for me, but I'll always pay someone to hold a light stand for me for personal reasons, so I just have them work the power for me.
I pay neighborhood kids to hold my lights for me and to be my gopher. It's my contribution to my community. There are several kids around me who aren't very fortunate, so I'm able to help them out and mentor them along the way. It keeps them out of trouble. Sounds somewhat irrelevant, but it's something I consider when I purchase my equipment. It's something I believe in and something I lilke to pass along.