Personally I feel like the next PT will be even a bigger gap then from The Incident. No offense to that album in any way, but it didn't feel like PT did much "new" with that album in terms of sound. It had a very clear Porcupine Tree-sound, a little from Stupid Dream/Lightbulb Sun, a bit from Up the Downstair/Signify, the heaviness of Fear of a Blank Planet, and some characteristics from the other albums as well. So in that sense the difference might be big, from FOABP. (which was pretty different then the earlier albums sound-wise)