m05 weight
The m05 with lipo (3200) and regular electronics comes in at about 1260 ready to race. An m05 balanced with light electronics and titanium screws in the l version (lightest version) comes in at 1258. Since you have to add weight to an m03 to get to 1250, the difference is basically 0. The m05 is less prone to traction rolling and wear tires much more slowly. The only hopup the m05 might need is the aluminum steering rack to take away slop.
All that said, when both are setup, they are about the same speed.