You may want to include the Western Mountaineering Flight Vest in your comparisons although I doubt you can go wrong with any of these choices. The are all great companies. I have the Flight and it's very warm. One of my insultaing combinations includes the Flight vest and a MEC Fleece 100 Jacket (11 oz). This works for my 3 season trips in the Sierras for elevations in the 8,000 - 10,000 foot range. If I think it will be colder or I'm predominatly on ridge tops I'll opt for a WM Flight Jacket. I should note that get cold very easily. I also tried a Montbell Down Sweater Vest but it was a joke in comparison.

I believe the Helios is a little longer cut and probably a little warmer. That Skaha looks a little pricey.