It is a common misconception that wearing snowshoes makes you actual "float" on top of the snow; you will always sink into the snow. If you have the 30" Lightning Ascents and you weigh under 280lb with a pack on and you are sinking into the snow, then unfortunately the tails will not help you much.
Sinking into the snow in shoeshoes is part of the parcel. Don't believe me then next time your snowshoes start to sink-- take them off and take a couple of steps, you will soon see that they are doing their job. The tails on a 30" shoe won't make a difference to the "sinking in" that you are experiencing unless you are a pretty big guy or carrying a pretty heavy pack.
At the end of the day, you will always get some sinking, but you won't posthole and that is the difference.