The Uni Signo DX (UM-151) is claimed by some to be even better than the Pilot Hi-Tec-C! It comes in 0.38mm tip size.
The barrel and tip are a bit sturdier than the Hi-Tec-C, which might explain why converts love them. Users can enjoy clean and even flowing lines, and the strong tips can withstand all the heavy handed writing you can offer.
Like all our other pens, the Uni Signo DX is highly sought after by artists and writers alike, but difficult to find in the US.