At my airline (not EK) I routinely fly with people who call "positive rate" without so much as a look at the baro altitude tape/rad alt. These are mainly light twin guys who have not been taught properly and think getting the gear up is the end-all-be-all. Poorly trained, and not really 'switched on' types it seems.
If you look at an IVSI during rotation it can indicate a slight, momentary descent before settling up into the positive region. Simply a VSI pointing above zero is not an indication of a positive climb. For all one knows the mains haven't come off the ground yet. Gear-lock solenoids makes a nice click when the weight is off wheels, but again does not mean you won't settle back onto the earth with a windshear or engine failure.
bottom line; use all cues available including looking out the window. Airmanship.