I tried to drag something to see if I encountered the problem you explained, but I didn't understand. After reading on I discovered that I already used the method you described. Obvious to some, for others, quite useful I can imagine.

I've used the "thumb trick" for a couple of months but I had to stop as the thumb was aching too much (even today it aches just thinking of doing that movement…), I even had to enable click-to-tap as I was not able to physically push down with the thumb.

And yes, I've enabled three fingers dragging as well. And as Dan says above I've noticed the short delay, that I find very useful.

And on 10.8 the dragging-lifting-dragging seems to work even better.

I've found the best solution to this problem for me is to enable click-to-tap and drag-locking. This way, once I begin a drag, I can continue to use the keyboard with both hands until I decide to complete the drop.

I don't know if you're aware of the existence of dragondrop, but I find that it solves the complex-drags problem for me quite nicely. It's a really simple tool, but has become essential to the way I work, to the point where I miss it as much as I do 1Password and Alfred on computers that don't have it installed. :)

Dan (above) is correct: there is a slight delay after lifting your finger, so one can continue the drag after repositioning. This annoys me once in a while when I'm selecting text and forget about the feature, since cmd-C (copy) is ignored during that delay.

I tend to use my index finger to initiate a drag, then continue it with my middle finger if necessary (yes, that finger is useful for something besides expressing yourself).

It seems to me that on my MacBook, using three fingers to move items around allows a short delay to lift your fingers and begin an additional movement before it drops the item in place. I too used to do the hold with one finger and move with the others, but this was a pleasant surprise. You may have to turn the feature on in the trackpad settings.