We have done this several times and in most cases we used this when for example the total area was not suitable for a vacuum sewer system due to different ground levels or we used this option if one of the buildings is to far from the vacuum mainline and is was more cost effective to use a...
I would recommend to look at : www.quavac.com
They take care of the design of a vacuum sewerage system which is the most important to have a proper working system.