My situation. I work for company A 1. My 6th yr H1-B ends in Dec 2011 2. Labor approved (PD May 2010) and I-140 (applied Sep 2010) pending - EB3 3. Once my I-140 gets approved (hopefully) my lawyer's plan to apply for a 3 yrs extension some time next year (Till Dec 2014). After/If I do get my extension for 3yrs with my company A, then Can I change my job to company B in 2012(who is willing to do my labor and I-140 again).
An extended H-1 can be transferred, but obtain the extension before the former employer revokes the I-140. I see no issues (generally speaking) with a PD transfer, unless USCIS (not the employer) revokes the I-140. Ask your lawyers for details.