Stick with the standard shifter set up. I ran the paddles for half a season, then made the switch. Boy do I wish I would of changed before the season even started.
The problem is the amount of time and strength it takes to shift a gear is far greater than the standard shifter. I would say you can downshift threw 3 gears with the standard shifter in the same amount of time as one with paddles IMO.
My Trackmagic kart came with paddle (butterfly) shifter. It sucked ass! The problem was that the upshifts pulled the cable to shift and worked pretty good. The down shifts pushed through the cable and was pretty worthless. Sometimes it would downshift and sometimes it wouldnt. I think a double cable setup would have worked pretty good, but I lost interest in that idea and put in a standard bump shift system purchased used off of ebay for a song.
I build boats for a living. We use a lot of control cables most of the paddle shifters I’ve seen use a Morse marine style cable. There are different grades Standard and Teflon. The Teflon is better but the most important thing is the geometry of the linkage. The system needs to be set up to use the full travel of the cable which is normally around 3″. If you don’t do that then your putting a higher load on the cable and your exaggerating the effect of the play in the cable. The right cable in good condition with the right geometry will shift fine.