DO they really reduce the analysis time in 1/3 or 1/4?
  Compared to what?  VERY roughly speaking, the 2.7 micron solid-core packings seem to give about the same plate height as a 2 micron totally porous material, which is about 60% of a 3 micron material and about 40% of a 5 micron material. Which means you could use a proportionally shorter column to speed things up. Other things.being equal, you're then looking at about 1/2. If you compare to a 10 micron material, then it's better than 1/4.
On the down side, the solid coreaterials are arguably less.tolerant of overloading.