Paul, look at Dans latest version of Pure Evil:

http://strickenone.proboards99.com/index.cgi?board=teambv&action=display&thread=308http://strickenone.proboards99.com/i...isplay&thread= 308

Its basically the same as Nitro-Gene 4/5, apart from the shape and two less motors.
It needs tracks, and therefore the extra 10kgs, in order to fit all that in, and that is with two less motors than your 100kg robot.

Food for thought...