I Disagree
It it illogical that after you become a PR and have at least worked for your sponsoring employer at the location of your LC that after this that you cannot work in another location with the same employer. This could be simply be the result of changing business conditions and clearly both parties (employer / employee) have a good faith intent to attempt to continue their permanent employment relationship. If the employee wasn\'t able to be flexible about location after fulfilling his / her PR obligations, then the employer may well then lay-off or fire the employee because he no longer has a position for the employee at the original location. How is the possibility of that better than the employer accepting a transfer with the sponsoring employer? Is that the desired consequence? I think not.
I work for a Fortune 100 company that moves people around all of the time and I have specifically asked our immigration attorneys this question. They concur that once an individual and the company have each fulfilled their obligations of the PR job offer, the employee is free to change job duties and location with employer -- with no limit of "X" months after becoming a PR. I suggest you check with your own legal counsel and not depend on our opinions here.