Climb gradients
max lenz-
V2 speeds, which are driven by Vmca and Vs considerations are not the best "steady state climb gradient" speeds. It is simply a speed chosen to maximize a number of different concerns. Getting off the runway, missing obstacles, noise, etc.
A greater flap setting will get you off the runway quicker, but you sacrifice gradient capability. Once off the runway, you must consider obstacles. A lesser flap setting (with the steeper gradient) is better for distant obstacles, but the greater flap setting will help you miss the closer ones.
For any given flap setting, the published V2 speed sacrifices gradient capability. The best gradient capability is roughly V2 + 20 or 30 knots. The best RATE of climb is even fster.
So if the airline you mention is using 1.4 Vs, they are using better gradient capability than most of us. I'm sure if that is approved, that the obstacle data has been calculated for that takeoff condition.