Years ago I extracted lot's of heather honey.  I did not press any.  With
heather, even extracting is a trick as it is so thick, uncapping and spinning
won't do it.  I had access to a machine in France called a picatuse (sp)
which inserted small needles in each cell and vibrated just prior to
extracting.  It was an extra step but sure was good honey.
 
Sorry, no experience in pressing.
Ed