I'd say it's a toss up. I ran a 6 foot Landpride on my 3940, and I'm now running a 7 foot. The issue is dragging the weight up and down the hills. I would look and see what the difference is in weight. That's what I did it in Landpride it was 50-100 Lbs different if I remember correctly. The other thing to look at is the price of replacement blades. The 6 foot blades you can get aftermarket and are pretty reasonable. The 7 foot blades are OEM only and pretty expensive. I was looking for the biggest cut so I could maximize my cutting time.