I agree with Dr H on the subject of the holes. The more the better. if you dont need them then you can always fill them with something there are plenty of "liquid metals" about. As for the clearence holes my MT2 gears come nearly flush with the bottom of the chassis and my rally is lower still so i would need that hole there. if your worried about dirt and stuff getting into the spurs then get some left over plastic from bodyshells and fix to the bottom of the chassis. Hpi MT2 chassis come with a part moulded specificically for this and fit the FF pretty well.