I have the 30e and do not find it ponderous and it is a 7 speed, the paddleshifters work in the same was as the ICE vehicles. I haven’t tried the boost function as the cars 322 hp is plenty with just a quick press on the accelerator. The Granny cable is no longer free but if you look on eBay you should be able to find a BMW one.
Example
https://www.ebay.co.uk/itm/116099605...Bk9SR5ao4LjIYw