I think there are two aspects to this:
1. shape (+ size)
2. stiffness/materials
1. I think there is a benefit to being on a less-than-pro shape/model when you are a less-than-deep-shortline skier. As others have stated, a ski one-or-two levels down in the product lineup will be more stable, forgiving, and ride better in the turns at slower speeds. As @Stevie Boy hints at, your boat speed affects things, so when you see a manufacturer's size chart, if your weight is near the upper limit for a particular size of ski that is designed for 32-34, you might want to consider sizing up a little if you are going to be skiing at 28-30.
2. Despite all that, if you are skiing the course, in my opinion, you still want a relatively stiff ski made with good materials. Lower-level skis are often made with little or no carbon fibre and cheaper materials to save money. If — as is becoming more common these days — the ski you're looking at comes in two versions, one with cheaper materials/layup and one with stiffer, choose the stiffer one. When you finish your turn and need to get to the next buoy in a rush, you'll be thankful. Stiffer, lighter skis (combined with good technique) take a lot less effort to generate speed.