To be honest, part of the reason Logitech went with that setup is because of the way that Eagle coded the behavior of the TDC when it's bound to an axis. What Eagle coded is that a displacement of the Axis equals a displacement of the TDC, which, even with a very high-quality pot, is just difficult for a human to deal with. So, most of us decided to use the throttle sliders for the TDC. Trouble is, MOST potentiometers, unless you want to pay $50 each, plus $150 for a good power supply, will create the sort of inaccuracy that we all have seen when using the throttle sliders for the TDC.
Anyone play EECH? Anyone use the EECH Central mod package? Those guys coded it right. (With respect to the geniuses at Eagle) In that implementation, a displacement of the mini-stick equals a rate of movement of the TDC along that axis; i.e., the further you move the stick, the faster the TDC moves, and once you release the axis, the TDC stays where you put it, and in THAT implementation, the mini-stick works BEAUTIFULLY.
It all depends on how you use it, people. ;)