What difference will straight cut gears make?

Straight-cut gears can transmit more torque than helical gears because there is no axial thrust component. IOW if you have two helical gears, one driving the other, there is a force trying to push the gears apart. This uses up some of the power, also it requires stronger bearings and a stronger case to hold the gears together. Straight-cut gears don't push each other apart. They're also easier to make.

The disadvantage is that they're a lot louder. Helical gears mesh in a small percentage of each tooth at one time, but with straight-cut gears the whole tooth is meshed. And for the same reason, helical gears can transmit more torque! Plus it's harder on straight-cut gears when meshed/unmeshed in a transmission.

EDIT. Wait. I said straight-cut gears could transmit more torque and then I said helical-cut gears could transmit more torque. That can't be right. Let me look it up.

HELICAL gears can transmit more torque. My bad.

Straight-cut are cheaper to make . . . . helical developed to reduce noise and provide more contact area.