You can find lots of information on this question. First off, you should know that tips sell cheaper now because they are less desirable primarily for two reasons: 1) Most (not all) would say they take the fun out of driving a sports car and 2) a significant impact on the performance of the 968. If you look at period road test articles on the 968 you can see that the tip shaves 2 seconds off the 0-60 time of a 968 (6.1 vs 8.0). That said, if you are just into cruising and not so much into shifting then why not. If you find a nice tip then go for it. They come standard with limited slip and there is only one issue with them that occurs at higher mileage. 19% of the coupes sold were tips and 28% of the cabs so they are out there and although they cost over $3000 more when new you'll typically find them selling for 10-20% less then a similar 6spd. Don't forget to join the Porsche club and the club 968 register when you get a 968. Let me know if you have any other questions.
My Tip. is down. Whenever I read of someone's problems in the forums, my 968's must sense the trouble with their brothers and immediately trash the same part. Usually when it is an absurdly expensive or involved repair.
My dampener went out this morning, I was 65 miles from home so I couldn't trade vehicles right away, and on my way to help my buddy out with his Toyota. Luckily the dampener will still work, just make a lot of noise at idle, unless you put the trans in neut.
My 6-speed decided to trash the odometer gear, not something that will keep me from driving it, just a pain. I fixed the odometer on the tip., should have known to just go ahead and order three odometer gears to avoid the hassle, but I figured "what are the chances?" How much do I know anyway?
Luckily the 951 must feel just enough like a red-headed stepchild as to not be as affected.
I have a 92 tip and as noted by Ken, the damper plate is an issue and has gone on mine twice. It cost around $1700 to get repaired at a shop. However, the second time mine went, the shop that works on my car converted my transmission to use a clutch pressure plate (from a 944 S2) instead of the damper plate. That was three years ago and I have had no issues at all with the conversion. BTW, the conversion cost me about the same as repairing the damper.