FWIW, I've got Live Gold on both my III and FM9, everything still sounds great and is certainly usable. Some things are different but it's not such a huge variance that it changes things in a negative way. In general, I use those presets like having a well-stocked studio, so when I'm recording and think "This part needs an old Marshall", I just pull up a preset, tweak it to fit the song and press Record. And actually, I don't believe I've updated Live Gold in my III for quite a while, I'm more than sure I'm missing the last update Austin put out.
The tweaks are so slight, they're just doing what I'd do in post with an EQ, or adding an effect to the preset.
I'm recording a song right now using the new beta and still using Live Gold the same way I always did. I wouldn't hold off on updating at all. Especially now that Austin's pointed out where the biggest changes will pop up, ya know what to expect.
(FWIW PT. II- I think Live Gold should come in every Fractal unit out the door. FAS would have twice as hard of a job keeping units in stock if it shipped with every unit from word of mouth alone. No dis to the factory presets, but Live Gold has been invaluable to me and the organization is OUTSTANDING)