We have trouble printing some quite large pages (around 3000 lines of html) getting the following error, running it in console verbose:

prince: Converting document...
prince: used font: Arial, Regular
prince: used font: Arial, Bold
prince: used font: Times New Roman, Italic
prince: used font: Arial, Italic
prince: warning: no glyphs for character U+0308, fallback to '?'
prince: used font: Arial, Bold Italic
prince: internal error: pack_blocks: empty list.

We are using Prince 8.1 rev 3 right now. Should I try with rev 4? Is there any way to get some more debugging info?

Yes, please try rev 4, as this includes a fix for an internal error caused by very large floats on small pages, which may be the issue here.