I too personally use pole gaffs..............
They tend to work great on the thin barked trees, but they certainly do kick out on the thicker ones unless you have your knees so far out that they may as well be behind your head. But they still work. Just make sure that you have your lanyard/flipline in place before you head to high!
However, this aside, they serve their purpose and due to the reletive cost of new ones, I imagine that I will keep using them on all trees for the next while........ I am like you DDM in that the spikes are not used daily, therefore, I happy with what I have.