pfSense

All new computers have the ability to boot UEFI afaik. There are few little changes that need to be made to pfsense to support some of the new challenges presented by UEFI booting. Previously, we could boot any machine that supported x86 with the same binary bootloader, so only supporting a single file was all that was necessary for the most part. With UEFI, we actually load a different binary depending on whether we are booting i686 or x86_64. This is totally supported by the DHCP spec, and you can see a low-level configuration example here.

https://access.redhat.com/site/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/Installation_Guide/s1-netboot-pxe-config-efi.html

In this way, we don't have to keep a static mapping of mac to bootloader files. So I would think that all you have to do is ginger up the network booting dialog to support per arch boot files, at least in the general DHCP options page.