it all depends on wich rim and how big holes you want to make. of course, you shouldn't just drill some holes in your rim cause you feel like it but if you masure a bit, looked up on a DX32 from 15mm holes to 22mm holes you'd save around 54% more weight, but still it'd just be a couple of ounces all this about rotating weight, i dunno about you guys, but my trials bike aint rolling too fast anyway so. if youre not harsh on wheels, have a heavy rim and feel that you have the time over, go for it. but i bet you wont feel any diffrence