I think the title describes it all. With the HOT temperatures we've had recently (26, 25, 28 on consecutive days this weekend) I was able to assess the winter toll on my plant collection. Low was only -23C, but the excess winter moisture, long thaw and cool early spring really hit hard.
The following plants are 100% dead:
Yucca brevifolia (5 years in the ground), Y. thompsoniana (both), Y. whipplei, Dasylirion texanum, Y. alofolia.
Opuntia splendens (polyacantha??), O. vulgaris, O. trinchophora, O. fragilis brachy., Echinocereus x roterri, E. triglochidiatus (from J. munro-cape), Cylinropunia spinosoir, Hesperaloe parviflora...
The following have between 20-50% survival chances:
Agave parryi 7000+ feet, Az(top killed, may come back from roots), Yucca glorisa variegata (probably dead, but spear looks OK), Opuntia cymochilla 'exquisite'... Others may be switched to this category.
Damaged but alive (50-99% chance of survival):
Yucca harrimaniae (outer leaves brown, inner fine), Opuntia phaecantha (Munro-Cape), Phyllostachys aureosulcata (small plant) 90% top kill, should come back from roots, P. nuda 80% top-kill, should come back from roots, R. hystrix burn to c. 20-30% of leaf tissue, spears firm, T. fortunei brun to 80-90% of exterior leaves, inner leaves fine and spear firm.
Not phased by winter:
Yucca elata, Yucca glauca, Y. filamentosa, Y. neomexicana, Miscanthus floridus 'gigantus', Magnolia virginiana australis (still green!), A. triloba, most cacti...

It's always hard to see a plant that you've had for a while die unexpectedly in a mild winter... That brevifolia has been my prize for the past 5 years. I know that it shouldn't be hardy... I guess it had a good run:( I think I learned a lot from this winter... It's not necessarily the extreme low temp that will kil plants, prolonged wet can be just as deadly, if not more so...
Cheers,
Paul