I started out in winter 2008 with a pair of gray Denali Ascents, with the optional 4" tails. I liked these shoes - they took a huge beating and kept on ticking. After several seasons with my size 13 boots, the binding material was getting worn, so I called Cascade Designs and they sent me new ones, no problem. A few more years go by and after 4 seasons, the plastic decking has cracked near the shovel - where it is narrowest. Another call and they replace them, no problem, with Evos (no more Denalis in stock). Unfortunately, the Evos are too small for my size 13 boots, so I kept those and bought the 24" Tubbs Flex Alps.
Denali - I locked the heel strap with a pan-head bolt and nut - this gave me consistent foot placement. However, getting the tension correct with four straps was not always easy and the shoes tended to twist a bit under foot, especially while side-hilling, and on the way down, my foot would slide forward and the toe of the boot would get caught on the front of the boot opening, causing them not to pivot, and when I landed, I would get a "crunch" sound as the plastic shoe was dragged across the toe of the boot. The crampons on these shoes took a severe beating and were in fine shape even at the end. I always carried a replacement pin and split ring, but never used them. The 4" (and one time I borrowed 8") extensions were not great as they threw off the balance of the snowshoes.
During the SSW48 2012, the Denalis died, were warrantied with the Evos, and ultimately replaced by 24" Tubbs Flex Alps. The Flex Alps bindings are easier and more secure, don't twist or slide forward, however, the friction system that holds them tight is not perfect and they did require occasionally tightening after a few seasons. I had a deck rivet pop (holding on the edge rails/teeth) which I'm told was common. I replaced it with another bolt/washer/nut. When a plastic strap guide broke, (25 months, 1 month out of warranty) I called Tubbs and after a pleasant conversation they agreed to send me new parts. When replacing the guides, I noticed the crampons were stress-fractured/metal-fatigued. Another call resulted in the complete binding piece being replaced. These shoes are not quite as sturdy as the Denalis, IMO. Tubbs is rumored to be of less help on warranty claims (only 2 years versus lifetime with MSR), although they helped me being just out of warranty.
I give the Flex Alps a slight edge on traction - which is great most of the time, but also means skiing down in powder in them is not as easy. The flex nature of the shoe ensures that more of the traction (teeth) are in contact with the snow/ice. I do like the televator on them much better than the MSR - easy to put up and down with the tip of my poles, no tab to float around (unless you duct tape it in place). I bought a pair of 28" Tubbs Flex Alps at the end-of-year 2014 closeout sales so I would have the bigger shoe when there was deep unbroken snow to deal with.
HTH,
Tim