I have used my Vex FL 8 SLT for 12 seasons now. Bluegills, Walleye, Perch, Whitefish, Lake Trout are my normal winter target species, with Perch and Walleye my focus.
In less then 75' of water I noticed a small delay in the screen from when I lift my bait to when it actually leaves the bottom on the vex. Very subtle delay in my opinion. Active Walleye I see come in with seperation, usually I entice them to bite with a lifting quiver action, so I see them rise up to take my bait. There are times when fish hug the bottom, I notice a flicker on the vex, lift my bait, fish comes slightly off, but then returns to bottom. Very difficult to see them when they hold like this, but I notice something different on the vex, and these fish usually I have a tough time getting to bite anyway. This is where the zoom would come in handy so you could see that bait right on bottom on that suckers nose and maybe entice a strike.
Perch come in on bottom as well but I notce them with the screen flicker, as they usually school and I usually can tell there mood by the lifting action. I mostly fish the 30 - 50' water for perch and use a perch rig with 4' of seperation between my hooks.
If I was in the market for a new vex, I would take a good hard look at the zoom feature, just so I have it if I need it in those slow situations. It could make the difference between taking home supper or taking home pepe le pu!