Hello. I'm still very new to the forums, but I think I can help you out.
Having owned both and used both at work (I work in a warehouse), I can tell you that the cyclone's steel will take a much better edge and hold it much longer than the tenacious. The tenacious is much easier to sharpen, but I found myself having to sharpen it after every two workdays whereas the cyclone could go well over a week without getting so dull as to be rendered ineffective.
As for comfort, the tenacious is quite a bit lighter and I find it's pocket clip to be superior. In spite of the fact that the Cyclone's aluminum handles are a bit more slippery than the Tenacious' G10, the Cyclone is a much more comfortable knife to use if you find yourself using it extensively. I have a row of callouses along my second row of knuckles on each hand from where the Tenacious has rubbed and caused blisters.
The cyclone's assisted feature (for me) broke after three months, after which I used it as a manual folder. I got a replacement torsion bar from Kershaw, but for my money, the Cyclone makes a better manual folder than it does an A/O. I find that the Tenacious' opening hole is an easier method of opening, although the cyclone's flipper and thumb studs are by no means inefficient. My cyclone's lockup was infinitely superior to that of the tenacious - the tenacious had a bit of blade wiggle from the factory (didn't affect the function of the knife, to be honest, only an aesthetic issue) and could be made to fail (with the spine whack test). Still, they both functioned well enough to make good work and EDC knives, which is all one can really expect from a knife, right?
In summary, the Cyclone is a higher quality knife with much better blade steel than the Tenacious. In my opinion, it would be worth spending the extra money to get a Cyclone, especially if you plan to use it hard.
Hope I didn't make a fool of myself :foot: and I hope I could help you make up your mind!