Popay,
There is no Commanders discretion with an Engine Out SID. If the engine fails and an Engine Out SID is provided , it must be followed.
Also, it says in the Jeppesen blurb which stems from Pans Ops (Part 11, 2.5 Contingency Procedures) that Operators are responsible for the developement of contingency priocedures, and that in the case of an Engine failure, the normal action is to follow the SID where terrain and obstacles permit.
I hope this clears up the muddy waters somewhat,
Regards,
CK.