In the unlikely event that you are just concerned about shifting then the inner stop screw can instantly make your triple into a double and you can loose the inner ring too. Then you can just shift all the way in or out for front shifting your "double".

There is definitely some weight to save with a crankset upgrade, especially of you are willing to spend money on a whole new drive train. If you are going to spend a lot of money, then consider upgrading the wheels and tires. That is often a relatively good way to go to save weight and/or make aero gains.

For us I doubt it would make much difference as long as the drive train is shifting well but if you want to go that route then my vote is for wheels then cranks.

On a pure weight saving side, dummy stoker hoods usually run 1/2 pound or so. Lighter stoker bars without hoods is a cheap way to save weight IF the stoker agrees.