urgent!! should I downgrade to EB3

worked for Company A and got PERM EB2 and I140 approved, priority date is 03/2011. Then left A and working for company B, but company B does not submit new PERM yet, hopefully by the end of the year.

 Company A would like to submit I485 (downgrade to EB3) for me.  and it costs additional money to downgrade and I485 but no way to get green card soon. So EAD/AP is just for a backup, no plan to use them. In current situation, does it worth to downgrade?

No plan to use EAD/AP. But what is the consequence if we used EAD/AP,  can my new company still file EB2 PERM based on my priority date? 

I really appriciate your suggestions and have to make decision soon!