Got mine installed today. I don't really have much to add to the others that have already posted.
I have to concur that removing the cap is a gigantic pain, and some might not even be able to do it. Also, as some have posted, pulling the linkage off takes a lot of force and is pretty difficult. Taking the battery and box out (while it is irritating getting at the third bolt behind the box) makes it a lot easier.
As for the results; huge improvement. I agree that it probably isn't a 50% reduction (although shifting from 2 to 3, 4 to 5 feels MUCH shorter), but shifts just feel so much better. Crisper, shorter, and it just feels a lot more solid and mechanical. It feels like a sports sedan should.
Also, the part being shipped from Badnews is the updated one, and has no issues in terms of the height interfering with the battery box. As long as you have the means to get it installed, this is the best $200 you can possibly spend on this car.