Is the highly optimized high subsonic cruise airfoil less safe for higher AOA flight?
The short answer, whales aside, is yes.  Such wings, called "supercritical"  because the critical Mach# is elevated, tend to suffer from leading edge stall that makes the aircraft's natural stall behaviour dangerous.  These airplanes typically require stick pushers (as @Peter Kampf mentions in this answer, the 737, even the later ones that got redesigned wings, doesn't really have a "pure" supercritical wing and I believe that's why they don't require stick pushers).

The Challenger business jets and the CRJ line of Regionals all have supercritical wing  profiles.  The profile promotes a pre-stall flow separation and immediate reattachment at the LE, called a Laminar Bubble, which would form at some AOA prior to stall.



This had an effect similar to having a stall strip or ice shape, with the bubble forming a trip wire so to speak.  It causes the wing to stall at the leading edge instead of advancing from the trailing edge, which meant the entire wing just let go all at once with no buffet or other warning, with a tendency to progress right into a deep stall.  The Challengers and RJs have stick pushers because of this; they must never be allowed to stall naturally, because it is probably going to be unrecoverable.  Bombardier did a lot of testing with various aerodynamic band-aids like vortex generators and vortilons and such, and they didn't help.

The CRJs larger than the 200 have LE slats and are just about unstallable slats out, but they also have the same LE stall slats retracted and still require stick pushers.  Flying with slats extended at high speed is out of the question. The drag they produce is massive, as you discover when you first land one after flying a hard leading edge CRJ200. Incorporating a fixed slot in the leading edge could be done but they are pretty draggy and would negate the benefit you're trying for in the first place, and I'm sure there are other mach related issues with a fixed slot.