Just installed a round carbon fiber knob (from NOPI).

Downsides:
-It's not really a CF surface. The CF is under a clear plastic cover
-It uses a universal plastic insert into which you cut threads as you screw it on.

Upsides:
-The round knob is a perfect shape for me
-The "cheesy make your own threads" method actually worked pretty well and didn't seem prone to threading wrong as I had hoped
-It doesn't freeze (burn) your hand.
-CF color is a great match for the interior
-You may be able to retain the locking nut (I didn't) without it showing due to a recess in the bottom of the knob.

Biggest Upside:
- The knob lowers the shifter height to just about 1/4" over the top of the shift stalk making for a very Lotus-like shifter position
- The shifter is very precise and flickable
- You can shift with your forearm resting on the console if you want.

Seems like a great mod!