Jim -
My take on the crampons/microspikes and poles/ice ax is as follows -
I'm a transplanted Vermonter living in the eastern Sierra, and I did winter hiking for years in mountains of VT and NH. A typical pattern there requires snowshoes for the first few days after a storm to pack out the trails. A week or so after a storm on popular trails means the treadway may have turned icy, so some type of gripper helps. Before microspikes, people tended to use 6-point crampons or stabilizers for conditions where a fall might result in bruising or possibly a broken wrist or ankle, but there was no real exposure issues. When crossing the occasional AV path, or above treeline where there was exposure, people switch over to crampons. So, on some hikes many hikers carry snowshoes, microspikes and crampons, and may use all 3 at some point during the day.
Microspikes have 2 primary advantages - they're light and you don't tend to trip as often since the spikes are short, so between the two people tend to wear them longer, which may result in fewer injuries overall. But, in situations where a fall may result in serious injury or worse - crampons are clearly the choice.
As for poles versus an axe - that's another situational issue as far as I'm concerned. Clearly, in a situation where a fall is likely to result in injury or worse if a self-arrest isn't attempted I use an ax. However, if the goal is not to slip in the first place, then poles have a clear advantage over an ice ax. So, sometimes I'll continue to use my poles when others are using an axe.
Here's an example - when doing Shasta via AV Gulch in May/June/early July, I use poles to Helen Lake and continue with them up to at least Red Banks. Usually I go thru the 3rd slot or even to the right towards the Thumb and if the snow isn't too hard will continue with the poles to the summit. However, if the snow is very hard, or I go left where it's steeper, I'll switch over to the axe until above Red Banks. And, the axe is out for the glissade down.
Another example - when doing Baldy via the Ski Hut, I use microspikes to the hut, and then crampons to the summit.
When Yaktrax first came out, they didn't have the strap over the instep, so they'd fall off regularly and I'd find them all over the trails. I guess they've improved them, so they might be useful for hiking (as opposed to walking across an icy parking lot) but personally I think they're are better choices for the same $$.
Microspikes come in different sizes, so don't assume your big ol' insulated boots require the large size. Fit them to the boots, the same way you'd do it with crampons.
Hope this helps.
