I am using both QGIS 1.6 and QGIS 1.7 r15108 from KyngChaos with the latest frameworks (GDAL 1.8) and have not had a problem with GRASS rasters, geoTIFFs, MrSIid, and Surfer GRID files. QGIS 1.7 does have some issues setting colors. This is fixed with new raster provider. This is using OS X 10.6.5. Royce