I'm sure that 212man intended to say that Vtoss can tend to, but is limited at, Vy.
An increased Vtoss can be used to eliminate a mass limitation due to first segment performance - at the expense of increased Take-off Distance Required (clear area / runway operations). At the limit - i.e. Vtoss = Vy - the first segment and level acceleration are eliminated as the helicopter is in the second segment climb configuration when it achieves Vy.
It is more usual to provide tables with reducing Vtoss - to limit the take-off distance required; thus reducing the size of the required heliport and airspace (short field / restricted area).
More modern RFMs provide tables with variable: TDPs; drop downs; reject distances; Vtoss; and take-off distance required, thus profiles can be configured to meet the constraints of the take-off site. This can permit the pilot (on the ground) to tailor the profile and mass to the more limiting element of the take-off site.
The latest helicopters already permit these profiles to be flown accurately by the autopilot (once the TDP has been reached and if a Vtoss is used) thus minimising the distance required in the event of an engine failure.
Wind accountability can be used in the calculation of some elements of performance (and that is why regulations require it to be factored to 50%).
Jim