Hey there atomicpunk78, Grafter,
So far, it has been holding up very well. I never got around to cooling the tower, and it really doesn't seem to need it. The amount of beer in the line from the freezer to the tap is so small that unless you are drawing an ounce or so for a sample, it's fine.
The tile is actually just placed in, not adhered in any way. That way, if I ever feel like changing the color, or if one of the tiles breaks, I can unscrew and remove the coffin, and slide in new ones. It takes some patience to get the clearances just right so that there aren't gaps, but it looks nice. A little sealant in the seams is a good idea for the inevitable spills, however.