L1 extenstion after H1 COS approval. Status now?

I need your esteemed help in clarifying my tricky sitaution.

I entered US in 2010 on L1A. It was expiring in Jun 2013. I have applied for H1B with other company(B) and it was approved in May 2013. It was a Change of Status. And my L1A extention was applied and approved in Jun 2013. However, I wanted to go ahead and join with Company B to be on H1.

Interestingly, current employer wanted to file GC petition in EB1 category(since on L1A). Now, GC looks to be more clear for my career… I wanted to stay my current employed and did not join with Company B yet.

Could you please advise me on what type of complications I would face by going ahead with GC applciation? I know its not good to play around with statuses, and I did not have any intention to do so… but GC option gives me more clarity and I want to stick with it and serve current employer… pls help me. Thanks in advance.