If you've looked around and read forums about the Invert Mini you might have seen people talking about the stock trigger on the Invert Mini.  The Mini's trigger does have some play to it out of the box.  It is adjustable at three points allowing for fine tuning to match your preference for trigger pull.

Personally, I agree that the Mini's trigger does have some play to it.  In fact, I am already looking into trigger upgrades myself and will post my review if/when I do purchase an trigger for my mini.  However, I don't think the stock trigger is really all that bad. Honestly, when you're in one of the ramping modes you don't need to pull the trigger all that fast to hit the max balls per second and even in semi-automatic mode I don't have too much trouble double tapping the trigger fast enough to acheive a decent rate of fire.