Very good points made so far e.g. keeping paper from squirming, cutting thin slivers of paper.
I have a Keencut Ultimat Gold and use it for its intended purpose of cutting bevels and straight cuts in mount or mat material. When cutting paper e.g. plain printer paper there is a tendency for the paper to bunch and crease slightly where the blade first touches (hence the need for a pristine blade). Same with the Logan cutter I previously used.
For cutting paper, photo papers etc IMHO a rotary trimmer is hard to beat. Rotatrim make excellent trimmers albeit a little expensive. I use a Dahle Pro model that is easily up to the task but not quite IMO up to Rotatrim quality of build. The Dahle trimmer has wall mounting holes in the base and I am going to fabricate a storage shelf for the Keencut.
If you can consider getting both