Quantum GIS and postgis - experiences?

Hi list,
currently, I am working mostly with GRASS-vector data, but I would like to 
know more about usage of PostGIS within QGIS. PostGIS seems to offer many 
GIS-functions, but which features are implemented in QGIS? Who is using 
PostGIS, and what are your experiences (for example with large datasets, 
geoprocessing...)? Also, I did not find the SPIT-plugin in QGIS 0.8 prev.2

I would be grateful to read your comments...

Best regards, nice weekend!
Wolfgang