Saw that column. Egan's right on the mark. Five bikes is perfect. I need three more....My all-time favorite motorcycle columnist -- Peter Egan -- wrote a column several years ago where he tackled this very topic. Peter's take was that 5 bikes were the perfect number to own, and went on to justify his reasoning. Egan says that every motorcyclist needs a dirt bike, a dual sport, a sport-tourer, a standard, and a cruiser/touring bike.
I need to go dig that column out again. It's in his book "Leanings".
Keep the rubber side down.