Both gdal_translate and gdalwarp can transform rasters from a PostGIS raster to all GDAL-supported formats. To get a complete list of the supported formats, you can use the --formats option of GDAL's command line as follows:
$ gdalinfo --formats
For both these GDAL commands, the default output format is GeoTiff; if you need a different format, you must use the -of option and assign to it one of the outputs produced by the previous command line.
In this recipe, you have tried some of the most common options for these two commands. As they are complex tools, you may try some more command options as a bonus step.
