I just finished a project with Arnold from Core Audio. It's also a plyKRAFT 4L.
I spent a lot of time thinking about which direction to go for a replacement to my Finite Elemente rack. I looked at HRS very seriously, along with Stillpoints, Grand Prix and a few others.
The main thing that I wanted was a very, very stable rack that I could put a Minus-K platform on to support my Spiral Groove table. A friend suggested Core. It took me a long time to actually make the call, but once I did things really clicked with Arnold.
I feel that I have a custom rack that is super beautiful and highly functional. It sets the foundation for my system. I am totally thrilled with it.