Steve,
I started a separate thread when i first got my 24W. it can be found here
There are a bunch of photos from my trials with the 24w, as well as a final product from a project I was commissioned to make.
In my humble opinion, yes, the 24w engraves better than the 7w. I get consistent engraved depth across an entire design where as the 7w merely etched the surface. As far as cutting goes, I have only messed around with .25 in maple plywood, but i can get through it in a single pass and the kerf is very even and clean.
Hope this helps,
Erik