I actually find it easer to do it the old fasion way with the sissors. I find the cutter and mat a PITA, im so unco at the cutter that i make a mess with the fabric, and very time i go to do it its blunt or something else is wrong with it. i find with sissors i get a nice clean perfect cut exactly where i want it.
in saying that i havent done too many projects that have heaps of fiddly pieces or are massively large...so i can see how sissors would make your hands sore etc.. so when i do start taking on the big guns.

good luck with your future projects!!!