We have a GIS staff of 7, and another group of about 14 who "use GIS" from time to time. We really, really want multi-user editing. Mostly of a large point file, and we're almost never in the same location, so editing the same point is not a concern.
I'd prefer everyone on ArcGIS, using ArcSDE, but we don't have the budget, or using QGIS and ArcGIS on PostgreSQL/PostGIS, but ArcGIS for Desktop cannot edit PostGIS without ArcSDE.
Currently, I've got the GIS staff on ArcGIS Advanced, and the others on QGIS 2.2. It's working well, multiple QGIS users are able to edit at the same time + one additional Arc user, but I'm always concerned about something popping up that I haven't considered. I'm backing up our data 4x/day.
Hoping there may be others in a similar environment who could help me learn from their experience, avoid making mistakes or losing data.
Best Answer
Since you would "prefer everyone on ArcGIS, using ArcSDE, but ... don't have the budget" you may be interested in "GISquirrel" http://www.gisquirrel.com which gives multi-user editing of PostGIS tables in ArcMap (at Basic licence level). This may give you what you want for all users, but if you still need QGIS in the mix then you are quite right to consider the effects of editing with mixed clients. The main and obvious advice is that you should always be prepared to recover from adverse incidents in your database, such as users accidentally deleting records, etc, and the more mission-critical your data then more fine-grained you want your recover capabilities. You might also want regular reporting of the vital statistics of your tables - number of rows, number of new/edit/deleted feature, etc to help identify any issues.
GISquirrel works differently from both ArcGIS+SDE and QGIS, though the overall effect is similar to QGIS in that edits are visible to all users immediately on saving.
GISquirrel checks out selected features for editing, and (optionally) can write values into the main table that “lock” the features and show who is editing them. The lock is only seen as a feature lock by GISquirrel though – other applications would just see a value in a field, though they could be customised to respect it.
On saving edits, they are written back to the main table. Only the changed/new/deleted features are altered in the main table.
GISquirrel also (optionally) manages feature-level metadata, showing who last edited each feature and when, which you wouldn’t get with direct QGIS editing (unless you used triggers and individual database logins).
I cannot foresee any problems with editing a PostGIS table in both (GISquirrel+ArcMap) and QGIS, so long as (as you said) you are not worried about potential editing clashes (where the later save would "win"). But we would recommend doing your own testing to verify this in your environment if you do intend to edit with mixed clients.