Give big applauds to the development team of ArcGIS 10 SP3, because of ECW and BigGeoTIFF with LZW compression with locally-customized spatial references eventually being supported in ArcGIS.
Of course, the enhancement of SP3 is still not perfect. For example, it still needs to re-define spatial reference (BigGeoTIFF, ECW) with ArcCatalog, before loading into ArcMap or adding into Mosaic Datasets. In other words, ArcMap still does not automatically or directly recognize some of the spatial references, including our local & WGS 84, without re-defining step with ArcCatalog.
Our tests were on BigGeoTIFF & ECW images, which are exported from preprocessed data by ER Mapper 7.2.x & 2011, Erdas 2009 & 2011.
