Matias quiet switches are quieter than any Cherry switches or most other mechanical keyswitches, but are indeed a bit louder than many rubber dome or scissor switch keyboards. To make any keyboard quieter, you can also stuff some kind of sound muffler inside the plastic case, and try to find a table that won’t resonate too much.
Both types of Matias switches feel almost identical (if you wore earplugs, you’d have to pay close attention to tell them apart), and are somewhere in between the weight of MX blue/red/brown and MX clear/green/black. Personally I wish they were about 5–10 centinewtons lighter, whereas MX blue would benefit from being about 5–10 cN heavier. Note that because the force drops away after the actuation/click point, whereas MX switches require increasing force as you press them further, comparing actuation force between MX and Alps-style switches is a bit misleading / not indicative of the total work your finger ends up doing.