I just deleted it and everything seems to function as normal.
It appears to prioritise booting from SD if the file exists on the SD card.
I just asked cause when new updates come out and i use the luma updator thing, is just gonna install to the sd anyway, so i would just have to copy to the ctrnand, unless someone updates it to have optional SD or NAND updates.With this update, you really don't need the arm9loaderhax.bin on your SD card.