PXE not working after upgrading to 2.5.0

Would either of the following work?:

1: With my (working) external PXE server, set MAAS as next-server for commissioning and deployment, or does the machine need to PXE boot from MAAS directly?

2: Could I replace the pxelinux.0 that MAAS uses with my older version, or with a new version that has the bnx2 driver compiled in? (And probably replace the initrd also)?