@Pumeco,

Geometric non-symmetry is not a problem for using the information as-is. The issue is that in .obj geometry vertices have no name or identification. Finding 'mirrored pairs' of vertices for copying vertex weights for example or morph paths is done by comparing the co-ordinates.  The search of mirror partners of vertices is done using a certain tolerance, they are float values and you canot compare on being equal like you can with integers. The margin is chosen large enough that pairs are matched with success, but small enough to avoid false pairs. Each time a file is saved and re-opened, a rounding off takes place which may set off position drift. Position drift therefore tends to grow with number of times the file is re-saved, Any synchronisation that worked correctly in the past may fail in later phases. Poser happily applies the mirrored info to any partner vertex found, but it does not warn you if it does not find a partner for a vertex, nor if vertices are left un-modified.

The value of symmetry is not for the rendering but for the identification, an aspect that is not part of the .obj specifiction. The root of the problem lies of course in symmetry information, when that is an explicit part of the design, is not stored explicitly. This however is the consequence of using a general purpose low level definition like the .obj format.