Here's a few comparison pics I took between the single pin BPI crimper and the 4 pin crimper from Reloaders Network. The BPI as leaves a thicker square shoulder crimp where as the RN 4 pin is a more round shouldered crimp. Id have to check but I believe the RN crimp is around twice the price of the BPI one so its up to you which style you prefer really. I will say the BPI crimper requires alot less down pressure it feels like. I put a RST 2 5/8 shell for next to them for comparison as well. I wonder if they use a RN crimper but just more shallow?
RN 4 pin left BPI 1 pin middle and the RST well clearly its marked as such