I used pine pellets too, but if you think that tracking is bad from that, the clay is no better! I'd much prefer wood pellets as well, but had to resort back to clay because I had litter box avoidance from one of my kitties recently. To rid of tracking, I can only say, sift twice a day (morning, evening) to lower the chances of sawdust particles getting on your floor.
For your concern with cats ingesting clay, I personally have had no problems with that with my two kittens. I've had them since they were 8 weeks and 11 weeks old. I too, worried about the ingesting but they seemed to know what that stuff was for. They both like to dig! What I don't like is that it's very heavy, usually dusty, and tracks a lot! I use the unscented ones, and as long as I scoop at least twice a day, and keep the box clean the smell doesn't affect me. I have one box in my bedroom, too. Might I add, they're eating raw now, so poop hardly smells, thank goodness! The good thing about scoopable clay is that you can actually see how much urine they are producing, and it's just faster to sift thru than the pellets.