I did the CA emissions removal on one of my 600RRs. On CA bikes the lowers connect in the rear to the evaporator canister mounting bracket. If you have a CA bike and want to remove all the emissions stuff you can remove the canister and replace the bracket so your lowers don't flap around. The canister itself weighs a ton so there is definitely a benefit in doing this.
I'd recommend against using CA lowers on a non CA bike because non-CA lowers connect in the rear and utilize more plastic making the tail-end of the lowers rigid. The CA lowers rely on the evaporator canister bracket to accomplish this. You can fab up a little tab (or zip tie) to connect the lowers but they will still tend to flap around.