I already have an adjustable mandrel and a mandrel saver, so I don't have any real need for this tool.
FWIW, if I didn't have either one, I would opt for an adjustable mandrel + mandrel saver over this tool because of the greater flexibility it offers.
Usually, I adjust my mandrel so just enough sticks out for the blank & bushings plus an extra half inch or so for the mandrel saver to slide over. With this configuration, I have essentially the same setup as this tool or mandrel-less TBC setups.
However, I sometimes like to turn both blanks of a 2-blank pen at the same time (especially for slimlines). In that case, I extend the mandrel out a little further so there's room for both blanks.
Even when I'm turning just a single blank, I will sometimes extend the mandrel out an extra inch or so and use a spacer just to give me a little more room to get my tool rest in a little closer.