Don,
Also compliments on an interesting angle of design for a P4.
...to you first post, I think the C-C approach should offer chance of a regulation par, very outside chance of a birdie (chip in - hole long putt) and a makeable bogey, whereas the A-A approach, should yield definite birdie opportunity, and straighforward regulation par - BUT - this is all relevant to the length/difficulty of the hole in question. I would imagine that 'most', (not the top 10%) of golfers would happily walk off the hardest hole on a course with a bogey, and try and make birdie down the last.
The 8th hole at Barnbougle Dunes is terribly difficult P4 for those 90% who dont smash it, rarest of rare pars would a C-C approach find, becuase the 3rd shot is blind to the surface, and sometimes the flag. So, to beat this great hole, A-A is the only way to make birdie IMHO, for most golfers, and a combination may yield a par or bogey - again, take the a bogey/par on the beast and try and get it back on either of the next two holes.
Does a P4 need this element to be great?
I think this gets into uncertain territory when the length of the hole is considered. There are some short P4s on Kyle's latest thread, that no matter what strategy you employ on any of these holes, but specifically the first and last ones, it will not make one little difference to the successfully overcoming the hole - so IMHO - this for me confirms there status as 'not great' examples of a short P4.
Now, if we take either 8 or 9 at CPC, both have the options available for any combo of C-C/A-A, and on both, given perfect execution, A-A should still lead the lower score.
So, for me, this lies at the heart of a great and strategic hole, where the golfer makes his way appropriately connected to his state of mind, super aggresive every hole, maynot always reward and can possibly throw you off your game, super conservative will not always reward with a regulation round, (as the golf gods all visit us each time we play) throwing you off your round - and certainly this must be an objective of the design, to unsettle, challenge, etc YES, a P4 will need this element, but it must offer the reward for the best execution of these approached for the lowest score.