H1 exp in Sept15, I have a approved I140 with the emp A, can i switch?

Hello!

I got transferred from L1B - H1B in 2013 after 5 years on L1B. H1 got approved till Sept 2015. Also, I have a approved I-140 application under EB 3 with a priority date of early 2011 with employer A.



Now, I'm getting an offer from employer B who is ready to transfer my H1 and file for my Green card application under EB2. I researched and observed that the current Labor and I140 process takes around 18-20 months. 



Question - 




	Is it worth to wait till next year and get my H1 extended from Employer A on the basis of the current I140?

	Are there are other areas to look for before switching to Employer B? Is it correct that Employer B will HAVE to file for a new H1 in April 2015? What is i140 is not approved till that time? 

	What if Employer A revokes the I140 application immediately?


Please guide.



Thanks!