I'm not a fan. Or if nothing else, let's take some things into consideration.
In the real world, even thieves are stuck playing eenie, meenie, miney, moe trying to figure out which of a series of identical backpacks holds a purse full of diamonds opposed to a brick. They're still in the same boat judging between a five pound ruck and a thirty pound ruck.
Let's step out of the real world a moment and into FL.
A thief does have to guess the weight of an object when they pry.
A thief does not have to guess the weight of an object when they steal.
Most people don't wear their containers, but you can. One way to stop a thief from stealing your backpack full of consumables is as easy as wearing the thing. He's got to go through much more effort to grab it than he would normally. If you're able to see the weights of said containers, you're now taking the guesswork out of pry. Thanks! Might as well just have stolen it from my inventory were that the case.
Of course yes, you could get a cursed sack like UC said, or you could bind your containers using CPs or RPs. Or use non-standard containers. There's a cloak that you can put stuff in. An egg. And so on.
But all that was concerning Dale's addendum. Which again, I'm not fond of.
As for Fool Hardy's suggestion, what would the threshold be? Is 5000 gold a moderate amount to carry around? Is it "nearly empty" as we've seen people carry around hundreds of thousands on their person? Would the same rules apply to monks? Would it be based on your current carry weight?
This idea I'm more in favor for, but you can almost find out the same information by just stealing gold in the first place.