Pat,
I built one last year, but you will probably have to wait until next year to play it. It's in northern Minnesota, so you will also have to travel some.
I built it on a 320 yard par 4, feeling that length would best replicate for todays players the thrill MacDonald expected with a 220 yard hole. As it stands right now, we also left just a narrow neck of trees in front of the green, so most won't go for it, but it seems trees blow down, and eventually, I think more will. So many will either try to wedge on, or run a chip through the valley.
Almost certainly, the reason more aren't built is they really aren't practical,
1. Getting a good cut on a steep valley slope is hard, especially if not hand mowing.
2. The valley space and 10 foot either side is uncuppable, so if there is budget pressure, adding 1000 SF of green is questioned and frowned upon
3. Some golfer is likely to 3 putt and complain.
4. The steep slopes need a lot more water, so to maintain properly, the super will have to send out a hand water crew
I figured building it in northern Minnesota would be a plus on point 4, but we are waiting to see how much longer the valley takes to "de-ice" in the spring, and it may be another type of turf problem. If I did it again, I would make sure to face it south for better warming.
Let's face facts. Unless builing one for noterity of the course, or to make something completely different, it doesn't work as well as it used to, either for maintenance, or play, as no one runs the ball up anymore.
Here's my question: Just because it was a CB Mac idea, or even if it was once a great CBMac idea, does that necessarily mean its still one of the best 18 green ideas we could come up with today?