Attonreys don't encourage you to apply EAD, why? they can make money from extending H1B for u ( u can't extend H1B urself , it must be from ur employer), u can apply EAD urself withour the signature of ur employer, only $175.
the consequence is almost the same, when ur petition of 140/485 is denied...if ur H1B used up 6 year limit u are not eligible for extending H1B on a yearly basis ( AC21) .
if ur H1B has 2~3 years remained, and u want to play safe, u might want to keep ur H1B status.