With my rig I usually have a space free just to help airflow to save things from overheating. Unfortunately this leaves a 1U gap between my power amp and pod or tuner. So this is a great way to make everything look flush, friends now assume my rig is now bigger than it is! I just tell them it is a "Cooler" :P
For the price it is just worth having incase you need to sell the rack tuner on a rainy day. The rig doesn't look naked! Looks very smart with all black!
The only downside is due to the colour. If you have black equipment it's perfect. But in my PA rig it has a brushed aluminium look to it, so it'll stick out like a sore thumb. Some people this won't be a problem, but no matter how little money I invest into a rig it has to look cool as well!
A big positive for this is how creative you can get with it. Whoever wants to add extra inputs to rack equipment, you can buy cable extensions and drill the wholes into it. Glue gun the piece in place and you are good to go. That might be a little over the top! Personally going to put some pulsing LED lights behind it so it looks like the rig is breathing!