For me, I look at the tripod's stability for its intended use in two positions, which coincide with the three most common types of shooting positions: standing and other than standing (typically this would be kneeling, seated, or prone). Both the Comp 40 and the 3372 are incredibly stable in any of the positions other than standing. Whether you're kneeling, seated, prone, whatever, they both give you an incredibly stable platform and I would really be nitpicking to say one was better than the other, but all those positions have the legs extended minimally. I typically shoot seated a majority of the time, unless the stage or terrain calls for kneeling, and I find both tripods to offer equally impressive stability. Your "wobble zone" is minor, and with the TA-U-LC locked, staying on target is really easy. With the TA-U-LC, either tripod will let you get as low to the ground as the tripod is capable.
When I'm standing, I find my "wobble zone" increases a bit. This is where the Comp 40, and its larger diameter legs, really shines. It feels like it's a little more stable than the 3372 when the legs are fully extended. The 3372 is a great tripod and more than adequate when fully extended. I just think the Comp 40's larger legs feel a bit more stable. The 3372 is also about 1.5 pounds lighter than the Comp 40 because it has slightly thinner legs. If I remember correctly, the 3372's largest leg sections are 37mm, while the Comp 40's are 40mm.
I wish I could say one was far superior over the other and make your decision easy, but I can't. The only thing that really separates them is the Comp 40 feels a little more stable when standing and the 3372 is a little lighter. If you're not going to have the legs fully extended, either tripod will give you an incredibly stable platform. The price difference is only about $45, since you can get the 3372 with free shipping and the Comp 40 adds another $30 for shipping. If you're in a rush, I'd look for a 3372, since the Comp 40 isn't going to be available again until May. If I found a great deal on a gently used 3372, I'd really consider it as well.
