K. luciae is vastly more common than K. thyrsiflora, and for practical purposes the only one of the two which is widely available in cultivation (though plenty of the former is mislabeled as the latter, including in the database here). You can easily distinguish the two at the time of flowering, if not sooner.
I have grown K. luciae for years and it is a pretty plant. Given its propensity for producing offsets, I would imagine they would be easier and much faster than seeds. In some cases you need to separate the offsets regularly (like once or twice a year) in order to ensure that the mother plant continues growing. Flowering is terminal and leads to the death of the mother plant, as well as more offsets.
