Can you please advice me about the possibility of EB3 conversion after a I-140 RFE on EB2?

Country: India
Date of Joining with current employer : Jan 2006.
EB2 PERM Filing/ Approval Date: Aug 2006.
EB2 I-140 (Regular) Filing Date: Nov 2006.
EB2 I-485/ EAD filing Date: July 2007.
EB2 I-140 RFE received date: Sep 2007.

RFE reads as below.

"Please submit evidence which establishes that the beneficiary had at least five years of experience as a software engineer after receiving his bachelor's degree but prior to August XX, 2006. Since your evidence does not indicate that the beneficiary received his bachelor's degree until 2002, this does not appear possible.
If the beneficiary received a degree prior to 2002, please submit a copy of that degree."

My attorney interpreted the degree completion as year 2000 instead of 2002 as my degree certificate has 2 dates on it. Even though I have a total of 5 years of experience (2000 to 2005) , I have only 3 years of progressive experience between 2002 and 2005 Dec. I have to respond to the RFE now. If INS allows to convert this case as EB3,the issue is resolved I assume. My attorney is saying that, all he can do is request for EB3 conversion as a response to the RFE. He's also getting a modified job requirement letter from my employer to specify that the job requirements can be sufficed by EB3 rather than EB2.
Labor certification only says Bachelors degree and 5 years of experience. Its not specific about progressive. I have 5 years of solid experience as my degree was between 1996 and 2000 year. I was recruited in 2000 and have work experience from that point. I had one supplementary exams each which I had to write in 2001 and 2002 respectively.

What are the chances of INS agreeing for a EB3 conversion at this point of time? How should my lawyer request for EB3 conversion.
How can I keep my I-485/EAD without getting revoked due to I-140 denial.

Some people told me to file a new PERM as backup and while filing I-140 tie the old I-485 in order to keep the already filed EAD alive. Will INS agree to that always?

Whoever is reading this thread please advice me. I don't have many friends who are knowledgeable enough to help me in this kind of complex situation.
Thanks in advance.