addidional EAD info
From my recent experience with Baltimore office EAD, they want you to make infopass for EAD, check DL, and then look at your receipt and in the computer (maybe), if you have more than 90 days after EAD recpt, they supposed to give you interim EAD.
In my case, I came when over 90 days but in their computer my EAD application was approved (not pending) so they refused interim EAD (see my fromer posts) but I got regular EAD next week, backdated about 2 weeks back.
They actually did not wonder where is my file...and for EAD it was maybe 100 people coming to get it ar certain day and they processed everybody within 2 hours...
So if you will have problems transferring, your EAD will be pending and not approved and you should get your card. And if approved, you can make a promose with employer (I know it is sometimes not possible, they always want original card) and show the card later.
Actually I am not sure what they will do if your file will be not there and they find out, but from my experience it looks like they just look at the EAD receipt (issued by Service Center). lets hope for the best!