Thanks fellas, nice to have some good comments on something I put together myself rather than a fancy off the shelf board.
Alex, I'm not really sure how the MXR Classic Od would compare with a tubescreamer to be honest. I generally use my amps overdive as I haven't found any pedal that compares and the MXR and Crunchbox are there for if ever I just want to use my Crate PowerBlock into a cab.