Dan Herrmann and others,
Have we already done a thread on "what is a Redan?". If not, it's a good idea because there will be a lot of input and a lot of disagreement. For what it's worth, while #3 at Merion is definitely all-world and first class (especially from the new back tee box), it does not, IMO, display the playing characteristics of the consensus Redan holes that I have played - those being #4 at NGLA, #2 at Somerset Hills, #7 at Shinnecock and #11 at the now-NLE Links Golf Club on Long Island. #8 at The Creek is also named Redan but I've never quite seen how that played like the others. Actually, the green complex on the Par 4 #6 at The Creek is very much Redan-ish in terms of how the approach plays "best".
We did do a thread re: "what is a Cape hole?" a couple of years ago (or more?). Gerge Bahto was the star of that one (for obvious reasons) and the essential point to have gleaned was that it's all about a large portion of the GREEN sticking out over a hazard and, despite the importance of the tee shot on McDonald's Cape at National, it has NOTHING to do with the angled fairway over a water hazard that challenges the drive. At least that's Uncle George's take.