I have the last generation Geshelli and a brand new Modius as of April 2024. According to my ears:
The Modius seems a to be a little "toppier" and "thinner" than the Geshelli when driven via USB. I understand why some people use the word "clinical" in the sound output.
The Geshelli is rich, nice soundstage, and powerful via USB and optical in. The Geshelli is weaker when using RCA out (got a wicked hum) but the XLR out worked just fine.
However, if I use the optical in on the Modius things improve significantly to the point where I can't really hear the difference between the two boxes. The Modius has a better system of selecting a source.
Between the two I prefer the Geshelli even though on ASR it is not recommended... I just like how it sounds.