Thank you for taking the time to write about the UI in comparison to the iPod Touch. I'm thinking of upgrading to a J3 from my iPod Touch 2G.

Are you running the latest firmware for the J3 (2.25)? Also, adding Kizune's UI replacements really impact the performance of the J3? I was hoping to load the Leaf UI on the J3 if I end up getting it.

Actually, for some reason, I have the firmware v. 3.3, which was preloaded on the J3. Kizune's UI is pretty, and is just slightly slower than the stock UI when you're not playing music. However, when music is being played, every touch takes a second to register (if it does), and button presses are not very responsive. I blame the J3's slow processor/lack of RAM (?).
I'm still making up my mind about iPod touch v J3, so stay tuned.