Please take a look at the new, much improved Avid MC version 5, to be released in two weeks. I think it will keep you away from moving to FCP. Its offerings are very, very good.
Also, you absolutely definitely CAN upgrade Xpress Pro to MC, and it’s 495 USD in the online store. https://www.avid.com/store
Also, you can do this 495 USD upgrade from Xpress Pro to MC version 4 today, and you will get a FREE upgrade to MC version 5 in two weeks.
Yes, Automatic Duck would get your edited sequences, and some media, across to FCP. There is no technical difference between Xpress Pro seqeunces and MC sequences, so that should work just fine.
Automatic Duck in itself, however, is more expensive than the upgrade to MC for you! And as said, Automatic Duck does not take your bins and full source media, just your finished pieces.
Your XW8000 is a bit old, and it is no longer on Avid’s qualified systems list. So you can opt to get any qualified (or non-qualified, if you dare) workstation, whether it’s PC or Mac. As long as you stay Avid, you can go either way and you can always access any and all sequences, bins, media, and projects that you ever created on your Xpress Pro system and immediately open them and use them on your new MC.
You’ll save yourself a lot of heartache AND money, IMHO, if you stay with Avid.