I'm not sure I qualify as a guru, but here's my take on this.
First, I hope you sent AR-11 to INS HQ whithin 10 days from address change. If you didn't, I'd say do it ASAP.
Second, hire a lawyer and seek his opninon on this. My understanding is that in order to qualify for renewal of EAD you need to supply your I-485 receipt.
If you send this to NSC, they will be confused by VSC I-485 receipt.
If you send this to VSC, they may( or may not ) be confused by your new address.
Based on common sense, filing with VSC seems a safer option, however, this is not what you are supposed to be according to INS.
When you change address, you need to:
1. Send AR-11 to INS HQ
2. Call your SC and make them change address on your I-485. Now that may trigger transfer of your case to NSC( I think that depends on internal INS state your application is in ), which is what you priobably want to avoid by not notifying them of your address. The truth is, you need to eventually, otherwise you won't be able to recieve any notice regarding your application. Which is why you should definetely seek a lawyer so that you can work out a solution
Good luck