Brian,
If using the Category A procedures and (after TDP in the take-off or before LDP in the landing).
There are statements inside AC29-2C to the effect that the Category A procedure effectively modifies the HV diagram.
There is no compulsion to be within: (a) the take-off manoeuvre to 1000ft; or (b) to be within the landing manoeuvre before LDP. Hence the necessity to make the HV diagram a limitation if full engine-failure accountability is to be retained.
The HV diagram is a sledge-hammer to crack quite a small nut - as has been indicated in the past, there is usually only one provided and under the most conservative conditions.
Most are aware of the necessity to be able to operate like a helicopter and perform useful amounts of work; this is why there are exemptions from excursions within the HV diagram contained in FAR 91.9 and JAR-OPS 3.005.
Jim