I installed the short shift lever a few weeks ago along with the BMW E90/91/92/93 3 Series 'M' Perforated Leather Shift Knob w/ Boot. I originally installed just the shift knob (stock lever) and it did bring the height of the knob down by maybe 1/2" from stock and it felt nice shifting but not the best. I installed the short shift lever and it really brought the height down even further. But i do have to say that it feels better shifting with the short shifter. When shifting before the SS was installed I felt like I had to make an effort to shift fast in order to rev match, but with the SS installed I find it it just happens with my normal shift throw. I don't know if I was lazy in shifting before but it feels better now. Next step is to get the carrier so the shifter sits centre.
BTW I was able to remove and install without going under the car. I did everything from the inside of the car. Removing the clip wasn't that bad, it was harder putting it on. I had a pair of bent needle nose pliers which made it easier. Just shift it into revers so the pin and clip are visible to the right side of centre. I will admit that I dropped the clip a couple of time and even lost one (don't know where it went) but it can be done.
URLs are to the products I have installed and pictures are of the shifter in different gears