There's a lot of nonsense at every level. Especially when dealing with heterogenous infrastructure.
Some NICs support http. Some NICs support tftp. Some NICs have enough memory for a big iPXE, other NICs don't. Some BMC systems make next-boot-to-lan easy, but not all.
We almost always use iPXE in order to normalize our pxe environment before OS kickstart. There's a lot to it and quite a lot of little things that can go wrong. Oh, and every bit of it becomes critical infra.
