ironically, as long as the gnomes can afford to retrain, they arent THAT bad =)
last age we were a mostly orc kd, and warred a full gnome kd, our armies dropped about same rate, mainly cause whilst we lost 8-points/troop, they lost 5
and with their lower training costs, they were actually able to start pulling ahead in term of army after 48 or so hours
combined with NS, they shouldnt be discounted
rogue or warrior is easily the best choice for gnome tho
shep/sage are ok if you wont be using the stealth or faster attack time