Well, Morrey, you're the second person to comment here about using an ATC, so I'll guess I'll throw in my 2 pennies.
First off...I agree with you...what cleanup with a saucer? It's a beautiful thing.
Just for the record, but I'm not a newb to smoking, but I am a relative newb with the WSM...I got it for Christmas last year. I've been smoking the tasties for going on 20 years, having used a variety of cookers. I'm fairly comfortable with my techniques for just about any kind of meat that I wish to put the smoke on. And I most definetly don't babysit my cookers...temp swings don't bother me...in fact, that's more or less how I learned to do high-temp cooks...mostly by accident and just rolling with it.
I, too, and like everyone here, am results driven...but I also like to play with my tools.
Anyhow, the use of a clay saucer IS new to me...I've been reading about it on here & thought I'd try it. I liked it. Did I monitor, observe, play, fiddle and watch the temp? You bet, otherwise what was the point of trying something new and learn how to use it? Was I trying to "fix" a problem? NO!! I was learning how to do something differnt.
As for an ATC...well, I've looked into those and even asked questions about them on this site, but after much thought, I came to the conclusion....what's the point? At least for me. I don't do competition cooks, but if I did, I would definetlely have one. For me and my uses, it's overkill...and with the awesome results I've gotten with the WSM (both short and long cooks), I see no need for one.
Another poster made the comment that "to truly dial the WSM like an oven, get an ATC." I couldn't disagree more!! I was truly impressed by the quick response time with the clay saucer. And had this not been the first time I used clay, I probably would have let it be to see how long it took to stabalize again...but I wanted to play and learn. Would I have had to fiddle with the vents with an ATC? No. Would I have fiddled with the vents with water in the pan? I wouldn't have. Next time I use clay? Maybe, but probably not. And if this were an overnight cook, I would have cared less if the temp spiked, regardless of method.