This sounds like a VERY good idea to me. And as indicated above, the Americans have a lot of weight classes for combat robots. The ones that are most popular there are not the same as ours; here is a table of the entries in the 2006 Robolympics as of a few days ago.

Wt Class Entries

150 g 6
1 lb 29
1 lb autonomous 4
3 lbs 9
12 lb 17
30 lbs 16
60 lbs 20
120 lbs 24
220 lbs 12
340 lbs 4

And from what Ive read they are very powerful machines. Have a look at http://www.botmag.comwww.botmag.com. Here is an extract from one of their articles:

Advances in battery, motor, armor, and electronics technology have permitted quantum leaps in the power that is packed into the latest generation of combat robots. Driven by the pressure of a National competition schedule that includes about 50 events a year all around the country, top competitors are forced to evolve and improve their machines every few months.

Kevin Berry, who fights in the smaller insect weight classes, reminisces; My first 3-pound beetle bot back in 2003 was built under a cake pan and it held up pretty well. Now I use custom formed titanium over a Kevlar honeycomb and we still get beaten up pretty badly in competitions.
--o0o--

We are going to face some rough competion.