I finally got up to courage to try FastActivate and it appears to have worked as my old One XL is now working with the latest map 855.2934. Many thanks to Pietu.
With that said. I'd like to mention some odd things (to me at least) that happened, but maybe they are normal. Could someone comment on these please?
1. PNGnavigator/ttsystem option created a new PNDnavigator but ttsystem was untouched. Is this normal?
2. I ran FastActivate from the root directory of my old device assuming it was only supposed to operate on that device. I happened to have both devices connected to my PC at the same time and when all was done I found my new deivce would not operate indicating that it's map was not authorized. I successfully recovered the new device using the TT Home Restore function. So my question is, does Fast Activate check for available devices and operate on all devices found?
Once again, many thanks to Pietu for this great tool.