The issue is connected to the texturepack Sphax PureBDCraft 64x Mainline + RR3 Pack.
Fastcraft 1.6 has an issue with the mods used in RR3 -220.127.116.11 mainline + a few other mods. It crashes after RR3 has been loaded the second time, independently wether Fastcraft was installed or not when RR3 was started initally. Removing Fastcraft afterwards allows to start RR3. Reinstalling (including full removal of RR3 18.104.22.168) shows reproducibility of the issue. Former versions (assumingly RR3 22.214.171.124, cannot remeber exactly) worked quite well. I am not sure if its version or mod depending since the upgrade from 3.2.2.x to 3.2.2. included a change of mod choices which i cannot recall.
Another player reports that on his machine the crash solely appears when Opis + Mobiuscore is installed. Removing Fastcraft or Opis solves the issue without the need of reinstalling, however this doesnt work for me (as described above).
1st attachment contains crashlog for Fastcraft 1.6.
2nd attachment contains crashlog for Fastcraft 1.11-debug2