I have a Keeley that I used to like quite a lot.
I found it to be much warmer and more natural sounding than BOSS or MXR units I had previously but all of them added noise, even the Keeley.
I think f/x like compression are the first indications of digital eventually surpassing analogue.
Digital keeps getting better all the time but it still has a ways to go on quite a few other kinds of f/x.
Compression seems to me to be an early victory for digital as does EQ.
You can crank in quite a bit of compression with nowhere near as much noise as analogue units.
EQ as well.
I have a Source Audio that literally kills any other EQ I ever tried.