Sean and I have had this argument before but let's do it again...
I believe a great Redan has these playing charactristics:
Uphill, at least partially blind approach
Cross bunkers well short of the green
Significant right-to-left tilt to the green and surrounds
Windy site
Angled green
Green runs slightly downhill
Kick mound on the right that will feed a rolling ball towards the green
Very deep angled bunker along front left side of green. (The Redan Bunker)
Greenside bunkers on the right beyond the kick mound
Last, and certainly not least, very fast and firm turf so that the ball will roll to the green, and balls flown to the green will most likely run long.
Taken together, the tee shot on a great Redan makes you take all of this in and give much thought to the shot you plan to play. Shot shape, intended loft and rollout are critical.
I would use the above as a scoring sheet to judge a Redan. Sean would use each question as pass/fail. Downhill hole? Sorry Charles Blair Macdonald, you failed to build a Redan!
For me, I would take a lot off for being downhill, which is why I don't like the one at Sleepy Hollow. The one at NGLA loses a point or two for being slightly downhill, but there is an element of blindness since you cannot see the putting surface from the tee. And NGLA's hole scores very high on every other category. From the drawings I've seen, the one Macdonald built at Shinnecock was superb, perhaps better than Piping Rock's.