I think this is maybe getting a little pedantic.
With reference to the use of the word 'replacement' in the initial post, perhaps 'alternative' may have been a better choice of word. Replacement does sort of imply 'substitute'. Also, given that Lindsey is well known to have a very extensive and in some cases extreme repertoire, not many girls would want to be considered a like for like replacement for fear of causing disappointment or being asked to do things they are just not comfortable with.
With regard to the three girls under discussion so far being 'different', this term can be applied in two ways - they are each individual and offer a unique and 'different' experience from each other. Also, whether they are full time or not, they are also each very popular and as such can afford to pick and choose (to a greater or lesser degree) who they see. I'm not sure that money is the sole motivating factor for any of them. I've not seen LK, but certainly with Lindsey and Elle there is a strong element of their own sexual exploration and experimentation involved too.
With respect to Lancspunters comment as to whether LK would be interested in recreating the scenario mentioned in the original review - my understanding is that LK doesn't play with other girls, so I don't think that was a particularly contentious or opinionated point for him to make. No need for him to be an authority, just in possession of some pretty basic and readily available information about the girls 'likes'...