I prefer using a paddle but I did join SKCC quite some time ago. I have found my membership useful since it's sometimes hard to find someone on the air for a QSO, and the SKCC folks are almost always there. I make several SKCC QSO's every week and pass out my number and record their number. I likely have enough numbers to qualify for one of the SKCC awards, but am just too lazy (right now) to make it happen. That doesn't mean I won't in the future. Generally, like most CW ops, SKCC members are courteous and easy to copy.
My K3s has separate jacks on the back so I have both a paddle and a straight key (and I can plug a bug into the straight key jack, if I want) available instantly. Sometimes, SKCC folks answer my CQ, even though I'm using the paddle (I find this out when they start sending an SKCC number, even though I've not specifically called CQ for SKCC), and I switch to the straight key in order to make the QSO legitimate under the club's rules.
I really don't see or hear from FISTS members on the air (I have a FISTS number, and indeed, have a FISTS Century Club number for contacting 100 other FISTS members). I will frequently look up my QSO partners on QRZ.com, and will find that they are a FISTS member after the QSO.
Is there somewhere that FISTS folks congregate? I certainly haven't run across it. I'd certainly pony up the minimal annual membership dues if I could find more FISTS people on the air that were specifically trying to contact other FISTS members. I know they have activity days, but I can't recall the last time that I heard someone call "CQ FISTS". Usually, when I'm calling CQ, I'll talk to anyone!

So maybe I'm part of the problem?