I'd like to run the kyosho spur, but its low on the list of must haves. When running with other nitros you certainly won't hear the metal on metal of the stock spur. However, when I run my e-crt.5 at the local indoor electric track I do get some stares because of the loud blender sound it makes. I tend to drive with my ipod on so it don't mean nut'n to me.
Whoops, I just noticed that there is an mbx5"R" out that is about twice the price of the sale on the original mbx5. I don't know how big of a difference the "R" makes, but I hate to start with an outdated buggy.
Still if the Mugen is that tough I'll keep it in mind.