Just out of interest, have you tried basic file access with 5.3.2f1, 5.3.2p1? I found file stream failed to read altogether with this latest version. Even something basic like File.ReadAllBytes(file_name) failed to load the data correctly. Previous versions the loading code was fine, but particles were broken... Some test code if curious (works fine in Editor, fails on 64bit iOS device):

void Update () {

string file_name = string.Format("{0}{1}test.txt", Application.persistentDataPath, Path.DirectorySeparatorChar);

if (counter == 0)
{
Debug.Log( "Writing file " + file_name );
byte[] data = new byte[10];
data[0] = 23;

Debug.Log( data[0] );

File.WriteAllBytes( file_name, data );

Debug.Log( "Writing file done" );

counter++;
}
else if (counter == 1)
{
Debug.Log( "Reading file " + file_name );
Debug.Log( File.Exists( file_name ) ? "File exists" : "File does not exist" );

byte[] readData = File.ReadAllBytes( file_name );

Debug.Log( readData[0] );

Debug.Log( "Reading file done" );
counter++;
}

}