As a fleet we do not perform many slat only take-offs and Airbus admit that there is an increased risk of tail strike in this config so there may be a slower rotation rate leading to a higher unstick speed,but as you say this is too close to a potentially critical limit.
... and this is exactly what your FDM program manager / safety department is (or should be) interested in: Find situations that pose a hazard that needs to be mitigated, and not to find proof that Cpt. X is a reckless pilot who needs to get fired and/or seriously spanked. You might even want to think about filing a safety report addressing this very issue.
