Compared to my Z4 M, the throws aren't near as positive/smooth, especially 5th and 6th. Other than that the 4,000 miles I shifted a 135i seemed fine, although I've owned many manual gearbox cars that were much better including a 1976 2002 (as you pointed out) and 2 Miatas. The short throws in the Miata were especially nice and very positive. I didn't replace the CDV in the 135i, which was probably a mistake (just to make the overall shifting effort better). Something I'm rectifying with the Z4 M. I'm just awaiting the part.
just mod your CDV, definitely takes care of the notchy feeling you can mod your own or purchase them for about $20, bmw sell the stock clutch lock valve for $16, then you need to core it out.
