PERM Denied, MTR & Briefing done, Is Employer change possible?

Hello,

I have a question regarding change of employer.
My PERM/LC1 was denied in June 2011 and MTR was filed by my employer. Later in 2012 Statement of Intent to proceed was filed and briefing is also complete and we are waiting for BALCA's decision. I received H1-B extension for 7th year valid till Dec 2013. The PERM is not yet approved by BALCA but can I legally change the employer now? and would I be eligible for another extension with new employer? Please let me know if anyone has faced similar situation or knows about the answer.

Thanks a lot!