I met a minor problem of layout. This is not due to DOCman but to the tool I used to make the template (Artisteer is not using Bootstrap unlike DOCman and Joomla). I contacted the team which was very active to analyse the problem and to try to find a solution. It seems that they might not find something reliable to overcome the Artisteer limitation (which is not under their control) but they committed to try to do so.
To summarise, the support service is really excellent. It may be considered as a normal thing for a commercial component but this is not seen everywhere.