Gentlemen....
The issue of V1 is a touchy one. Many operators have different policies, based on their individual experiences.
One thing to note, depending on when the aircraft was certified, the V1 issue is different. As stated above, we're supposed to have something like two seconds reaction time...and still be able to get it stopped. But, this is based ont the new certification standards (both JAA and FAA).
I'm not sure about the NG737, but the older ones were certified under the old system...whereas, you really need to be transitioning to the 'stopping mode' at (or before) V1. Under the old certification standards, any speed above V1 (in an abort scenario) is not good (e.g. two seconds after reaching V1).
The Bus, on the other hand, even though it was produced under the old set of standards, meets the new criteria. That is, you can actually 'initiate' the abort at V1...and still have runway to get it stopped. "Initiate" means, you recognize the need to reject the takeoff (at V1), and promptly do the drill. Again, under the old certification standards, you don't have this.....under the old standards, you really need to have the stopping process going for you as you reach V1.
I can't remember exactly when this certification change occurred, but I'm thinking it was around the early nineties. Again, not sure about the 737NG, as it may still be certified under the original 737 certification rules.
From a practical standpoint, we're talking about only a couple of knots. Sure, as stated above, screen height is affected to some degree, but not significantly...i.e. not nearly the difference of 35 feet vs. 15 feet (dry vs. wet).
Of course, this is all based upon a 'balanced field length'. Some might define 'balanced field length' as "You're dead if you stop; you're dead if you go!" Again, in practice, if bad things happen near V1, you need to be "go minded" as Boeing and Airbus (both) recommend. Who defines 'near V1' is why we have stripes on our shoulders.
Fly safe,
Pantload