Dear Olaf,
I tried V_V2 and it was working fine. Make sure it not in simulation mode.
1) Sales order is created. RDD is 01.11.2015. Current stock is 0.
2) Schedule line confirms for 30.11.2015
3) Run V_V2. Make sure it not in simulation mode.
4) Log confirms that new date is on 20.11.2015
5) Delivery date successfully changed automatically to 20.11.2015.
I hope this is what you are expecting from the system. In that case V_V2 will solve your problem.
Best Regards
Hussain