Well I took the plunge -- bought Vocal Planet, Logic Studio (upgrade from Express 7), AND the new Leopard OS, and have installed all of them just in the past few days. Am happy to report they all seem to be "playing" very nicely together, with one minor exception:
I attempted to install the Soundfinder app from Vocal Planet's Data Disc, and discovered it was a "Classic"-only app. Went to the Spectrasonics site right away to download the OS X version of Soundfinder -- which I have to think must exist by now -- but couldn't locate same.
Anyone know where I can get it? (Or can it be that in late 2007 there still isn't an OS X version? Say it isn't so!)
Here's the (unexpectedly fast) reply I just got from Spectrasonics Tech Support:
This does not exist nor is it necessary. SoundFinder was supplied on OS 9 because the MP3 format was relatively new and players were not commonly available on operating systems. It is not necessary for OSX because the Finder should be able to play the files directly and other MP3 players are readily available.
Guess I had the idea that Soundfinder was more than it really is (or was). So apparently everything's fine, and it's full speed ahead.