APT backup has worked for me on several occasions - as much with a 3GS as with a 4, and with my new 4S. I just transfered 4 to 4S a couple days ago and it took me ten minutes to get everything like before. It even keeps a certain track on layout and some settings. You'll have some job to do, but everything will be there. SB settings still had all my toggles in the same order I had them set, Winterboard held all my used themes checked and in the right order, Springtomize kept its settings too. Bytafont still had my fonts but I had to set them back again. I had to hide a couple of icons again (activator, remove BG) with SBsettings. Longest part was to set up my folders to what they were, half of the apps were just scattered across the springboard... But Multicon Mover made it quite easy.