I haven't done of ton of preset crafting, I maybe made 6 in amplitube 4, but they worked very well for my needs.
I remember in one of the threads someone mentioned to keep AT4 because some things sound different in 4 than 5.
Having played around a bit, I decided to try importing my presets (all mesa boogie if that matters). They are drastically different and unusable in AT5. It's not a huge deal as I can still get what I need from AT4, but I was wondering why they are so different and which parts are the main ones that changed so I know where to focus most of my time in tweaking them should I try to make them usable in AT5. I took screen shots of the front panel and amp settings did carry over, so that's not it. Pedals also appear to be the same.
Also, as relates to presets, the recently released Slash "world on fire" one is perfect. You guys nailed that one. I was close in AT4, yours is dead on, even gets rid of my pick noise which too many presets seem to pick up.