Although in my re-testing of this tool with 3.0.8 everything seemed fine I have since noticed that it only seems to work for line-weights of 0.5 mm and larger!
using a line weight of 0.00 produces the original non precise result.

Is this expected behaviour or is something still not quite right for this?

see topic:
http://www.qcad.org/rsforum/viewtopic.php?f=33&p=7684&sid=6121271d19c37dd6454644eacb4d33c4#p7684