I have heard some conflicting reports on the reasons why some manufacturers choose to outfit their aircraft with stick pushers. I am aware that some aircraft have pushers while others don't. Does anyone have background information as to the certification process, and/or requirements that mandate some aircraft to have them (Gulfstream) while others do not (Falcons)? I'm curious to hear your thoughts on this subject, and specifically, if an aircraft has a stick pusher, does that mean it has an inherant design flaw if allowed to approach a deep stall condition? Thanks in advance.