Re: 929 to a 954
I didnt 'make the move', but I have both (at the moment). The 954 has a little more grunt on the low end, and feels smaller, but overall I love my 929 more. This may be a result of riding it 20k more miles than the 954. If you are considering an upgrade - spend the money on upgrades to the 929 and enroll in a few track schools. Take both of the MSCF courses, if you havent already and ensure you have appropriate gear.
Yeah, I know this really wasnt the answer you were looking for, but it is my honest opinion. IMO the 929 is way more bike than most people will ever need for street riding - so master it before dropping a lot of $$$ on a bike with more power, etc. Unless your a 'poser' and you just want the latest and greatest or you like the looks of the newer model.
Bottom line: Both are enjoyable bikes, but I would say its not worth the extra money to 'trade up' IMHO. I would honestly buy a black 600rr at the present, if I were to buy a new bike. ND??? I have an extra 929 I will swap you.