According to what you have said if I would like to use phone without encryption, then updating Xperia X to 3.4.0.24 is not possible using Sailfish OS UI, as UI OS update client will reboot the phone and activate encryption. If so, which way of updating would you suggest before deleting /var/lib/sailfish-device-encryption/encrypt-home to avoid encryption ? Reflash with 3.4.0.24 or update via terminal?
What is the probability that updates 3.4+n.0.xx will not break or again impose encryption onto the Xperia X?