Dan,
Have no fear, I was recently at Cape Kidnappers and I have a really serious fear of heights. At no time will you feel stressed about being up high.
Cape Kidnappers was a special treat for me. I really thought long and hard about whether it was going to be worth such a big chunk of my trip budget. I can say now after having experienced the course that it is certainly worth seeking out. The 3 courses that the Renaissance guys did in the southern hemisphere are all outstanding IMO.
I wondered how much variety there could be in the course with those fingers of land you always see in the pix of CK, but there is much more to the course than just those holes.
The clubhouse is very fitting for its setting and doesn't try to knock you over the head like so many monuments to pretension you see at high end clubs these days.
Paul keeps the course in fantastic shape and turf allows for you to play whatever shot you can imagine.
Plan a trip to include Paraparaumu Beach, CK, and Titirangi and I assure you it will be well worth the time.