This thing is perfect for me.
I produce at home and need to record high-quality sources. I externalize further processing and mixing to an engineer, so I don't need thousands of euros of analogue gear which only provide subtle sonic features, like SSL, API or their emulations.
I bought a full RME rig made of a Fireface UC, a Quadmic and an ARC controller. It wasn't cheap. Approx. 1,6k€ including studio grade cables and all. I could have bought other products with that money (Apogee, UAD, etc).
However, now I have full routing flexibility, a set of 6 preamps (2 UC + 4 Quadmic) plus several outputs and monitoring options, which are improving my overall workflow and allowing me to keep all my analogue gear plugged in at all times, while also using the UC on the stage.
The QuadMic preamps have plenty of volume, the analogue controls are straightforward, the unit is light and sturdy. Noise is low even at high gain settings. The build quality is at the RME standard, which is high.
I use the RME preamps for literally everything: Rode NT1000, Oberheim Matrix, my electric guitar and electric bass. The recorded material is industry-standard level, and I never heard anything sounding wrong.
Sure these preamps do not provide special textures like SSL or API, but they're cheap and light, and if your workflow includes an external engineer or further software editing this will not be a problem at all.