I have found the cause of one crash caused by destruction by weapons with "Feather Impulse Thruster 2x1" and "Feather Impulse Thruster 2x1b". And it seems some as yet unknown other part involving "PartAreaDamageEffectRules". I've gone through the part's components but couldn't find the actual problem.
This involves Abh mod 0.5.3RC2 and Abh mod 0.5.3RC3 with this simplified savegame file