The AWC will produce much nicer motion and better power control than any GRBL or Smoothie board. Smoothie is limited to one power change per millisecond, so it’s not technically possible to produce anything finer than 0.1mm dots at 100mm/sec with Smoothie - the firmware won’t do it without modification. GCode boards aren’t well suited for laser use because they treat everything the same - there’s no special handling for raster data, for example, so the barrage of tiny moves chokes the motion planner and limits the throughput. DSPs handle raster data differently than cut data, and optimize for this. If all you’re doing is cutting, this wouldn’t be much of an issue, but DSP controllers have better handling of low/high power as well. A CO2 laser has a firing threshold, and it’s simpler to set the low-end power value on a DSP system, and can be done per cut.
Depending on which AWC controller you got, it probably has a screen (possibly color) and will run jobs headless - You transfer to the machine, then the file is hosted there and can be run again without the PC. If the power fails, it will pick up where it left off.
On the other hand, with GRBL or Smoothie, jobs are streamed live, which can be troublesome if the connection drops, but can be a benefit because you can run jobs that would never fit in the memory of a DSP controller.
My suggestion would be to stick with the DSP for now.