at work i use twin rope, with the ses i use single, i'm comfortable with both knowning how hard it is to break a rope even exceeding the swl and good rope management and edge managament is essential in both,
what i'm trying to get at is if one rope fails, then if a rope is from the same batch, treated the same way by the same people there is no reason that it won't give way as well.
really its horses for courses, if i can work both then i'm pretty much safe with whoever i have to deal with