I've got some more questions:
1) Can this process be done again to put it back to 'MZ604_H.6.2-24_Retail_Europe' from 'MZ604_HWI69' if needs be and does this European ROM include Motorola's pre-installed apps, such as Quickoffice HD, MotoPrint, etc?
2) None of the guides say to re-lock the Xoom, whereas the Motodev instructions do. Is unlocking and then re-locking a one time process? What effect does it have leaving it locked or unlocked?
3) Once the US firmware is on there and providing I don't then root it, is the Xoom now a GED that will receive OTA updates from Google without any problems or do you have to re-lock it to achieve this?