Most of the modern Redans I have seen (including most of the six or so that I have built) are different than the original for one or more of the reasons below:
1. Modern architects learn not to drain the entire green off at one spot, and that's what the green at North Berwick does. So, you either see part of the green draining to the front right (that's why it's flatter than the original) or somewhere out to the mid doe ir back left behind the bunker (whereas at North Berwick the 16th tee is raised higher in that location).
2. Modern architects usually look to create distinct pin positions, and many times that includes a front hole location on the Redan, so they make it less steep in front. Whereas at North Berwick or National, there really isn't much of a front hole location, and the green is fairly plain, just a big long slope with raised edges.
3. Modern architects usually build the Redan in one of two settings ... a flat area where they can't think of a different idea (a la #7 at Chicago Golf Club) or sited along a natural ridge (a la #4 at High Pointe). In either case, it is unlikely that the ground at the back left of the green will be anything like what you find at North Berwick, where it is soft and gentle and nearly at grade, despite the deep hollows at the front and back of the green. That sort of land formation really only occurs on links ground where the deep hollows don't have to surface drain anywhere. And, of course, few modern courses are built on ground like North Berwick.
4. Few modern architects have EVER built a green which slopes away at 4% or more, like the real thing.
5. Modern designers try to build the Redan at 210-220 yards thinking it has to be that long if players are going to use a lower-trajectory club for
the shot to the green, but at that length, they also reason that the green can't be too severe.
6. Not many courses have the tailwind and the firm grind common to North Berwick, so even if you built an exact replica, it wouldn't really PLAY like the original very often.
By far my favorite of the ones I have built is the 17th at Pacific Dunes. I think it gets the entrance of the green just right, and that's one of the hardest parts. We deliberately made the right side of the green softer than the original because our hole was 210 yards and into the prevailing wind, but the other 3/4 of the green plays like the real thing. However, the hole only plays like the Nirth Berwick hole in the winter, with the wind straight behind; in summer it is into a quartering wind from the left, and there aren't many players who can hit a running draw in that wind.