Porter, the 30 tooth, while still considered by most to be a combination blade, lt leans more to the ripping blade (24 tooth) than the 40. The 40 is the truer middle of the road combination blade. If you only have one blade, then the 40 would be better. If you have a 50 tooth combination blade, or a 60 or 80 tooth crosscut blade, then a 24 rip blade or 30 tooth combination blade would be a good blade to go with it. With a 24 and an 80, you would have the best of both worlds, but should change blades for each type of cut. The combination blades give you the compromise of both worlds, and the number of teeth give you an indication of which end it favors. This is a very generalized synopsis of the blades. Hope it helps. And keep in mind,if you have a contractor saw, the thin kerf will work fine. If you have a 3 hp cab saw, you would probably be best served with the 1/8" kerf, or full kerf, blade. Hope this helps and is not too late. Most do recommend the stabilizer to go with a thin kerf. I'm going to try it without and see how it does, both cut and noise wise. Jim.