I have a Sigma 100-300mm f/4 HSM, which has been a decent lens,albeit less than perfect in its AF performance and occasional focus hunts for no discernable reason. The range and the weight and balance of the Sigma are both very nice. The Sigma balances very well on a bigger camera, with a battery grip on it. On a professional Nikon body, which weighs in around 3.5 to 3.8 pounds, the Sigma's balance fees almost 100% "neutral", and not front-heavy whatsoever. I mention this so you can compare the Sigma's length and weight specifications to those of the Tokina you are considering,and to your camera.I think a lens of this general size and weight demands a battery grip type camera, for less fatigue in the wrist over sessions lasting more than 20-30 minutes. I think the 100-300mm f/4 Sigma EX HSM lens is a good compromise between a 70-200 f/2.8 with a TC 1.4 added, and having basically the same max aperture but with slightly BETTER optics wide-open; you lose one f/stop, BUT the Sigma at f/4 is actually better than a zoom is with a 1.4x added. And, to make matters worse, the 70-200 lens with TC is "compromised" at each focal length UNDER 200mm....one really only gains the range from 200 to 280mm when using a TC 1.4x on a 70-200. So, in all, the better choice is to get a 100-300mm f/4 lens if you are going to need more reach than 200mm.
I wish I knew specifically about the Tokina, but the above is what I can tell you about a similar,competing product from another maker.