You want to PXE Boot? Don't use DHCP Options.

PXE is basically a subset of DHCP, so I am not sure that your point is valid. When you use IP Helpers for PXE, you are relaying part of the DHCP request. I am also not sure why you think an IP helper is only for one specific purpose. IP Helpers are a network technology supported by and used by multiple network vendors. It's not a "Cisco" technology. If Cisco's documentation says IP Helpers are for DHCP relay, then that would include PXE since again, PXE is a subset of DHCP.

Ultimately when you use DHCP options, you are splitting the PXE boot process between the DHCP server and the PXE server, which complicates things and introduces additional points of failure. Most of these failures are at the network level outside of Microsoft's control. Why would you do that when you can just allow the PXE server to handle the whole PXE request? Ultimately, a PXE request is a network request, so why wouldn't you handle it at the network level?

What I can say is that we have resolved thousands of customers over the years by having them switch from DHCP options to IP Helpers. Plain and simple, IP Helpers are more reliable, so why wouldn't you use them? There's nothing to "fix" here. Part of the DHCP option issues is the way OEMs implement PXE on the devices themselves, so it's not even a Microsoft problem to fix. You are welcome to go to the OEMs and have them fix the issue on all of their devices, or you can just use IP Helpers and have the problem resolved.

After supporting PXE for 15 years, I can absolutely that this isn't bad advice, and I have never had a single customer ever complain to me after switching from DHCP options to IP Helpers.