I have experimented quite a bit with the Microspikes, a Hillshound knockoff (called Mil-spec crampons) and regular old crampons. My first investment was the microspikes, which I liked and used daily on local hikes that had limited ups and downs. They work quite well on clear ice (I use them to run around on the lake) and they provide solid traction on packed snowmobile trails and wet spring ice. The biggest problem I have is that under extreme conditions they will "peel" off your feet (mostly to the sides). This can usually be avoided with some care, but traversing moderately sloped ice/snow can be somewhat scary. The safest method is to traverse sideways with your feet pointing upslope, preventing the spikes from peeling and better preparing you to fall onto your ice ax for a self-arrest.
Although not quite as tough in appearance as the Microspikes these: http://www.sportsmansguide.com/net/c....aspx?a=602151 seem to work very well because they have an extra strap that prevents the peeling mentioned above. I have not had to make any serious repairs in my use although I have heard of others who have (fixed with pliers though). They aren't quite as compactable as the Microspikes, but close enough. I only carry these for light traction now when I hike.
The full up crampon is useful and the general advice about treeline is reasonable, but I find that the crampons also work well on a packed but soft trail for the downhill trip. The crampons will dig deep into the soft snow and prevent sliding, but do not have the weight or bulk of a snowshoe. This use is limited, but often practical on the well used trails in the White Mountains.
In January I used Mil-Spec spikes for the summit cone of Mt. Chocorua since the ice was only 1/4 to 1/2 thick. The crampons would have been ruined and the Microspikes are too "peely" for the scramble up and down the summit cone. I used my full crampons for the hike down the Piper trail where the soft but packed trail snow covered the steep sections (between 1 and 2 feet of snow); allowing me to maintain a fairly fast pace for winter travel.