Both DXT and Uncompressed types are saving correctly
(from left to right)
Top Row: Original BLP file
Middle Row: DXT1/0-bit Alpha (none), DXT1/1-bit Alpha, DXT3/4-bit Alpha, DXT3/8-bit Alpha, DXT5/8-bit Alpha
Bottom Row: Uncompressed - 0-bit Alpha (none), Uncompressed - 8-bit Alpha
All that's really left now, are the Indexed (256 color) types.