Is the 1500ft acceleration height there for obstacle clearance or is it part of the company/ICAO standard noise abaitment procedure.
For performance requirements;
400ft is the lowest that the acceleration height can be.
The acceleration height may be higher in order to clear a relatively close in obstacle. The maximum acceleration height (maximum level off height) is the highest you can climb and accelerate to final segment climb speed within the take-off power time limit.
If the 1500ft is for obstacle clearance then I would agree with those who say that anti-ice should be allowed for in advance if required.....after all, you can not plan that your engine will fail at 400ft for performance A requirements.
If on the other hand the 1500ft is a noise limit then after checking the performance data, you may find that the minimum acceleration height for that airfield's obstacle environment is lower.
Just a guess.
DFC