I don’t believe in Bayes factors as measures of evidence, and it’s hard to apply them other than for a one-dimensional parameter. Instead, you can calculate Bayesian posterior probabilities from a two-treatment-parameter proportional hazards model:
- P(the two survival curves differ at any time t)
- P(the hazard functions differ at a specify time t)
- P(treatment effect is accelerating over time)
- P(treatment effect changes directions over time)