seems to me, the risk even higher if you do H1 transfer

Usually, most of I485 will get approved, if you do not have anything wrong before. But if you inform them you have already changed the job in first 180 days, the possibility of I485 denial or REF will be very high, base on my imagination. Even you get H1 transferred, but most likely, you have to re-start your green card process. As you said, it is tough decision.
I still think using EAD will be a better choice. However, it still depends on how much confidence you have for your I485 get approved.