I'm using a 8 prong and 4 prong stitching chisel, 7 spi with .8mm tiger thread. I think that the 4 prong makes a slightly larger hole...not much. I've been waiting on a set of Kevin Lee irons for a year now. I don't use the 2 prong much at all. Should I?
What do you mean by reversing needles? If I am, I don't know what it is.
I'm not using a groover. I've been using dividers to mark a line. Some say grooving weakens the leather. I pound the stitches flat with a cobblers hammer. I'm pretty new at this, but like the diagonal look instead of the drilled holes.