TempDb - Moving / Adding Files And Resizing

Have a SQL2008R2 instance on a VM where the single .mdf for the tempDb database is located on a high contention disk.  I've managed to get another 60GB disk and thought it would be a good time to move the .mdf and also increase it's size and number of files. 

The server has 12 cores and after a bit of reading I've decided that it would be best just to have four files for this database as the 1 file per core (-1) seems to be disputed.  

-- Move the existing file to the new disk and rename it.
ALTER DATABASE tempdb MODIFY FILE (NAME='tempdev', FILENAME='E:SQLData empdb0.mdf');

-- Change the size to 1GB
ALTER DATABASE tempdb MODIFY FILE (NAME='tempdev', SIZE= 1048576KB, FILEGROWTH=5%);

-- Add three new files, all with the same size & growth
ALTER DATABASE [tempdb] ADD FILE ( NAME = N'tempdev1', FILENAME = N'E:SQLData empdb1.mdf' , SIZE = 1048576KB , FILEGROWTH = 5%)
ALTER DATABASE [tempdb] ADD FILE ( NAME = N'tempdev2', FILENAME = N'E:SQLData empdb2.mdf' , SIZE = 1048576KB , FILEGROWTH = 5%)
ALTER DATABASE [tempdb] ADD FILE ( NAME = N'tempdev3', FILENAME = N'E:SQLData empdb3.mdf' , SIZE = 1048576KB , FILEGROWTH = 5%)

-- Now restart the instance.
 
Also, what are peoples thoughts on percentage growth for tempDb?  I've read that it's not recommend and yet it seems to be the norm.