Hi.
I just purchased this Aalto Plugin, and have been trying it in the VE Pro (32 bit) with Pro Tools 9. It's basically working well, but in combination with VE Pro, it's heavy on the CPU (30 to 40 percent with 4 instantiations of Aalto along with VI Vlns, Vlas, Cellos, Flute 1 & Oboe).
Aalto is a plugin that uses a basic idea from the (70's?) Buchla days, re: Mort Subotnick, so it's a nice idea for electronic composition. I haven't yet to combine the Aalto patches with Vienna Samples, but if you're at all into electronic sound creation in combination with Vienna, it may be worth a look. They have a functioning demo (all except saving) to try. It's only AU right now.