Side cut is more important than effective edge when it comes to turning. I believe both have very similar side cuts, hence I didn't feel there was any difference in the amount of effort required to turn the Believer or the Darkstar.
Something I just noticed, if you're hitting a lot of jumps and bombing down runs, the 155 is perfect. However, if you're looking more for a freestyle board, being only 143lbs, you might consider a 152. It'll still be pretty stable at speed and a little more playful for your weight range.