Noise seems like an odd reason to go for a moving bed! Compared to the cutting noise I doubt you'll notice much difference, but then I've never made a direct comparison of the two configurations so who knows.
Simply putting the machine in a box with a door with make a huge difference to the sound level.

Is there a website for those machines? That moving gantry machine has unsupported rails on the X-axis, can't see the Y-axis and Z has unsupported rails too. I'd steer clear of that ... if you want it to cut a decent feed and finish, or cut aluminium efficiently.