Hey! I said that!
Actually I was just browsing through the thread and trying to think of a good way to balance the weight.
A more expensive style of gas-lift strut has a resevoir attached that is significantly larger than the piston displacement, so they provide a relatively constant lift force. The cheaper gas struts like they use of car hatchbacks don't have the resevoir and they have a big difference in lift depending on the stroke position. Of course if your total stroke is only small (3 inches?) then the non-linearity won't matter that much.
Once suggestion I would make is to ditch the cast iron motor and get a much lighter router motor. There are many good routers on the market and most have variable speed control which is another bonus.