Guys, the man is asking a good question. Of course there are changes. If there were none, then you would not need to update/upgrade ever.
To the OP: I have some templates that I use. These rarely change because the template involves routing and effects. When I find a reverb I like, I save the BLOCK in my block library. Same with rotary, chorus,etc. I can then load these up as part of my presets. Most of the firmwares these days don't change the effects.
As far as the amp goes, I usually reset the amp block and go at it with a fresh ear. Sometimes I even change which amp I use.
For the presets that have to be as identical as possible as the preset before upgrade, my best practice has been to record a snipet with a DAW including the raw guitar data and then match this with the new firmware. But I only did this twice on the context of a recording project. As I do mainly live playing, I don't care about sounding the same as yesterday, I just try to sound better than the day before!
That being said, the changes over the last few presets have been less drastic and more refined. I still had to tweak certain amps, especially gain structure, but mostly, my presets were quite usable. Some just became simply awesome without having to do anything.
As a Beta tester, I try to check any other changes in behavior. Push the setting to extremes, try unconventional combinations, etc. to identify bugs. These days, it's hard to find some. The coding is obviously thought through very thoroughly and Cliff is doing an amazing job of keeping the envelope stretched far past what we thought would ever be accomplished, while remaining true to the performers so we don't have to re-invent the wheel every time.
Hope this helps.
