Some weeks ago, I committed a new version of the PostGIS Raster driver. The improvements were aimed to get a decent performance in data visualization. The driver worked really slow when used with QGIS or MapServer. We fixed this. And I say “we” because it would have been impossible without the help of Even Rouault and Victor González, from geomati.co. Most of the credit goes for them.
Apart from that, I’ve inherited the QGIS PostGIS Raster plugin, from Mauricio de Paulo (he can’t devote his time to it right now). I’ll keep the plugin updated with the GDAL PostGIS Raster driver itself.
The new version of the driver lies in GDAL trunk. You may want to give it a try. And send us feedback :-).