Happy with the demo, I just went ahead and bought G-player for use on my xp-64 system. It loads and streams perfectly so far. Unlike Gigastudio it doesn't do a long scan of the database, but rather browses directly (a la Kontakt). It's been simple and straightforward.
I ran 4 instances (16 channels each) inside the new cantabile 64-bit host and it was a dream come true for another frustrated Giga guy.
There's hope for our meticulously honed libraries.