Here is my experience with Alchemy in Logic Pro X 10.2
I was a little worried, because I was using the Alchemy 1.5 plugin on some music. So I first tested it on my old (mid 2009) macbook. Since I did not use it for logic since a long time, I first had to install 10.2, then download additional content, and after that I decided to install the 1.5 plugin plus factory content, which I still have as a pkg. I never bought any additional libraries, because when I tried I noticed Apple had bought Camel...
So I copied a piece of music with 4 Alchemy tracks ("Amplexus", "Hither and Zither", "Bell Keys B" and "Atomic Harmonic") and 12 others to my MacBook.
I was pleasantly surprised that everything sounded exactly as it should, and that my six year old MacBook played everything without any problem.
The old plugin appeared as "Alchemy 1".
Then I got a bit more adventurous. I copied the directory "Macintosh HD/Library/Application Support/Camel Audio/Alchemy/Presets/Factory" into
the directory "Macintosh HD/Library/Application Support/Logic/Plug-in Settings/Alchemy", next to other subdirectories like "Atmospheric" and "Basic".
I have written the file paths in detail, because it took me about 15 minutes to find them back when I wanted to type this message.
Then I changed the four tracks from "Alchemy 1" to "Alchemy". That's all I did. I got the new interface, and all four tracks played exactly as before. They were present in the new browser (I think they were not part of the original 14.1 GB additional download). Maybe I was just lucky with these four tracks. But even if I was, it was great to see that the old plugin still worked, even on a computer it was not installed on before.
I think Apple deserves a lot of praise for this. I was expecting Alchemy to appear as an in-app purchase, or as part of a new Logic Pro X 11.0 that was not a free upgrade. I was very much worried about incompatibilities. I have become very dissatisfied with Apple over the last two years, especially regarding numerous issues with iCloud syncing. But what the Logic Pro team has done here is just amazing. It is so fantastic that I do not even understand their business model anymore. Buying a company and giving all its products away for free? Maybe it is really true that they just love their customers?
Sorry, I guess the purpose of this site is to ask questions, not too make compliments. But I just needed to say it.