I got this:
http://www.cosmoracing.com/productin...id=133&pid=396 from ebay a few years ago. Seems to be a neuspeed knock-off but works fine for me. The shifts feel just like stock but shorter and a tiny bit tighter. I never used the Leanracing nor the Pspec shifter but I can't imagine it to be that much better then the adaptor considering the price.
Both the leanracing and Pspec shifter essentially replaces the stock shifter rod with their own rod which has the linkage point relocated to a higer point to achieve shorter shifts. I believe short shift adaptors could achieve the same result. I surely like to be proven wrong though by trying either a leanracing or pspec shifter myself.
Regarding your notchiness, did you shave off enough material from the console frame? If not, the shifter cable and the frame can rub and causes your shifts to be notchy.