By 'worth', I only have two metrics:
- Visuals & general aint-it-cool points
Watercooling might not be the answer.
- Visuals (& general aint-it-cool points) -> NZXT Hue
If the pump is inaudible you still have fans. The ones you already have are the best you can buy the only thing left to optimize is their speed. I would buy an electronic fan (and pump) controller first that can turn off the fans if the computer is idle, to see if that meets your noise goal. If you upgrade to WC it can use it ti control your pump(s).     
Watercooling reduces load noise far more than idle noise.
Hue = Coloured LED lights alone don't do anything for me.
And this is kind of the problem, that half of the people tell me it would be worse going WC, and half tells me that going WC is better, and it's been really hard to gauge their level of relative experience in terms of acoustics. The one guy I know who does know something about it who has actually listened to the existing rig said "That's pretty hard. Not sure if it's possible", adding that it's the quietest gaming PC he's ever heard and that he
wouldn't know where to start. But then although he's built WC rigs, they aren't what I call in the showcase league - and his
air-cooled system is pretty noisy. Not exactly sure what it has under the hood but I bet I could do a better job of it.
Maybe I was expecting too much but I was kind of hoping someone would jump in saying "It's easy, just put these bits together, guaranteed silence" and list the bits and I can just feed that to the builders. I want the glowy tubes...