I used that decrease on a hat recently and it worked out well. (I got tired of the "light spiral" look that you get with k2tog.) I did 6 CDDs every other round instead of the 4 you plan -- it was a pretty arbitrary choice, really. 4 should be okay too. If it looks like the hat is getting too pointy, you can always adjust your rate of decreasing.
There is no right way to knit; there is no wrong way to knit. So if anybody kindly tells you that what you are doing is "wrong," don't take umbrage; they mean well. Smile submissively, and listen, keeping your disagreement on an entirely mental level. They may be right, in this particular case, and even if not, they may drop off pieces of information which will come in very handy if you file them away carefully in your brain for future reference.