Moom has to be installed, not necessarily running. The AppleScript will open Moom if it is not already open.
But since there would be a Moom startup delay if it's not open, I always operate with Moom open.
The responsiveness you mentioned in your OP is enough to tip the scale for me. But even without that issue, I find many of the other Moom features to be huge time-savers.
Notwithstanding the aforementioned performance issues, this point is correct if you are referring to automation within macros and your scope is limited to simple window resizing and movement.
I find set-up to be much easier because one can manually arrange windows and have Moom read the positions and sizes and build a Moom Layout.
Also, using Keyboard Maestro and Moom together can be very powerful. For example, refer to: Use Moom Layout Sets
Agree.
Also, not as frequently as with Keyboard Maestro, but I sometimes call Moom Layouts using Alfred Workflows, BTT trackpad gestures, and Shortcuts.
In summary, Keyboard Maestro is my main automation pipeline, but I spawn other tools when I find their use to be more efficient. YMMV.