I'm cascading a remote WMS from Geoserver in order to have all layers in one place (and to exploit caching). (see the manual)
The remote layers (on this geoportal) are provided in multiple SRs (e.g. EPSG:4326 and EPSG:32632), and I get to choose which one I'd like to use when adding them directly from e.g. QGis. However, when I add the layer in GeoServer, it chooses one of the SRs without asking me which as the "Native" one (in my case, EPSG:32632)
I can get QGis to work around this by enabling on the fly reprojection, but I'd rather have the data right in the first place (in my case, EPSG:4326).