This will be interesting. I have auditioned many tube pre-amps before settling on the Herron, but I have not heard a Shindo, I would have liked to as my bias is that this is a company driven by passion for music. Given that, I can tell you my impression of the Herron and why I went that direction. The herron does not have a lot of tube coloration. It is very liquid, smooth and solid with tremendous detail. I find it well balanced from top to bottom without glare. My system does not reach to the very low 20hz range but does have good bass and the herron does not lack there. The herron is very very quiet. The pre I liked equal to the Herron was the VTL TL6.5. The VTL perhaps a bit more crispness at the very top, the herron a bit smoother without seeming rolled off.
I look forward to others input as well. For me Shindo wins on the cool factor, but the Herron is a really impressive build.