I did some digging into this and spoke with Traditions to ensure that we were fully informed before commenting on the forum.
After speaking with their engineers, they do not feel that it is safe to use the A1443 breech plug and 209 primers in the Northwest muzzleloaders. Due to the frame and barrel designs of the Northwest guns, blowback and pressures would be unsafe and is not recommended or advised on any level. Just keep in mind, this is straight from the engineers and I am just relaying this information.
Also, installing an A1443 breech plug in your Northwest gun will void the warranty on your muzzleloader, which is always a concern.
GOOD NEWS: Not all the updates were bad news! Traditions is releasing a conversion kit for Pursuit and Buckstalker muzzleloaders, to fully adopt the 209 primers. This kit will not work in the Vortek platforms, but at least anyone owning a Pursuit G4 or Buckstalker will be able to safely make the swap, without jeopardizing their safety or voiding their warranty.
Please let me know if you have any questions about this and I will do my best to provide additional clarity on this.