You'll love it!
The styles are in different places, or not there or new, so the Songbook won't be right. I found it easier just to start over with an entirely new songbook.
There are some styles that I liked on PA3X and PA900 that weren't on the 4X, but they are available.
I am not using the same e.q. I will take a look at my settings and get them to you. Can't do it now because I left it at work.
There are some name changes. STS is now Keyset. Performances are history; they are now custom keysets, but work much the same. I use totally Songbook for all my setups. It is very powerful.
Too sleepy to do much tonight. Let me know as you get into it and have specific questions.