Here is a little scary tidbit from those of us "going both ways".
We have the fun distinction of being able to logon to Flyingtogether using both employee numbers, which massively screws with most browsers and your ability log on next time.
It is amazing how different it is when we click on the same thing with each employee number.
Even the simple task of checking in for a flight, the method is different. I am amazed at how unmerged the two operations are, 3+ years down the road.
6 months here and I cannot make a non-rev reservation with my CAL number and no one can fix it. I still don't have a company email despite asking at the puzzle palace and sitting in my CP's office while they tried.

Not good.