I'm doing a fresh micro, the last two chips came unprogrammed.
I did modify the kitprog project so the built in 4200 in the pioneer doesn't have to be unpowered by removing the jumper. If you remove that jumper then the 5LP gets into bootloading mode.
I modified the kitprog project so that SWDIO uses pin 5LP0_0 and SWDCLK uses pin 5LP0_1, the internal 4200 is still powered but not present in the SWD chain. I end up with 5 wires same as the miniprog.
I use the /xres and 4VDD plus ground on that other header.
Only thing to be aware is to only upgrade the bootloader and bootloadable modules to 1.1 (comes with 1.0) and also the USBFS modules have to remain at 2.51 or 2.5 on the instances of the project. Upgrading those to the latest modules makes the kitprog not work.
So it's not just a hex programmer, I can use it as a full programmer/debugger and I can program and debug the external 4200s without adding a bootloader on them of course I can if I choose to, restore the bootloader on those prototype boards.
But since you already have a miniprog 3 I wouldn't bother much with this.