I used to be a valet as well, most fun job i've ever had. Especially since I was at a polo club with exremely rich people lol. I've tested tons of +- shifters and all seem slow and sluggish. Moms 300m, takes forever, sisters Mazda6, takes forever. Same with my friends C230 all slow.
I drove an 07 vette at rev it up with the paddles and when u are auto-X ing the shift time 2 second seemed like forever, same with cobalts but im sure it was better than a cobalt. I just kept it in 1st the next time around and that got me the best time. I have driven a maserati with paddles and that thing shifted fast! just like and auto when I hit the paddle, DSG. Went to return an M3 with SMT, that was FUN. but i didnt abuse the car so you can trust me to park your BMW's and stuff.
Im not trying to bash the autos and shifter devices, I just prefer clutchin' it and burning some rubber.