My experience of quick-shifter (no the super expensive on linked) is that they made the shift quality worse and slightly more recalcitrant, rather than a more direct feel as hoped. The shift in most Loti are not really any better, so..
Not all gearboxes are made equal, so perhaps the trade off from being generally robust, able to handle plenty torque, and relative cheapness comes at the expensive of ultimate shift feel. I'm sure there are methods for slight improvement (a brand new gearbox probably the best option!), but the F23 doesn't win any awards for shift feel in the Vectra or Astra..
This... most, if not all, the shift feel is down to the box in the vx220's case.
Short shift mechanisms mostly ruin things, as gm boxes tend not to like being hurried.
That all said, if people want to buy and try things, then all power to them.