Keeley Compressor

They are very high quality

They actually don't do that much, which is a good thing
it doesn't color your sound, but it smoothed it out quite nice

I now have the 4 button one, and I haven't played with it that much
but if you want a nice amount of compression, without knowing its
really there, the Keeley is great

I tried a couple of cheaper ones, and they sound more like an effect
the Keeley is very transparent

I wouldn't keep it on all the time
country players might

Can't remember anyones pedal board that I have seen live use a compressor
but along with compression comes sustain, helps get clean sustain

it's beneficial to use use to keep your note volume constant
if you pick really hard it will soften it, if you have a random attack
it will make it sound smoother...chicken pickers like that

I used it with my Bassman, tended to get rid of some of the ice pick
only helped sustain a little, loses just a little tone

I prefer to play without one actually, like clean unprocess single coil sound myself

cheers

me neither, the Boss squashed the living daylights out of my pick attack
but I got a bit more sustain....altered my tone way too much

the Keeley is much better for me

whether it's worth the $$, it's up to you

A compressor is a must.   You can't expect them to get you excited because the effects are subtle until you actually hear what you are striving for (often pre or post to another effect in the chain), then you realize there is no way in hell to go without one.  Many do not know how to actually use to get diversity from their instrument.  The ol’ MXR Dyna Comp was THE standard in the late '70's and all '80's and still sounds good but I think the Keeley is an upgrade on the concept.  Simple and sweet! It sounds like they are VERY meticulous of the design quality and that is worth its wait in gold with effects of any kind.
Plus if Jim M knows and recommends them I would trust completely...it's been years but maybe I'll have to take up playing again to find out! NPB just about EVERYTHING is recorded with compression of some sort and usually on stage rack effects too.  If the reverse effect is used (expansion) as a complement noise reduction (when I say "noise reduction" it means noise and ANY unwanted sound, that unwanted sound may be "wanted" in another circumstance or by a different person) alone is well worth the usage.  Sustain and feedback control are good.  Overbearing volume (in relation to other band members in the mix, yet still "hot" in the forefront like in a solo) kept in check, lots of practical uses!  Record and playback to train your ears if you think you cannot hear the differences in real time...Bypass transparency means nothing "leaks" from the circuitry into your sound  when you  want the sompletely "dry" sound...