I have used it in GB and DP5. Works great. It gives you very flexible synthesis options. Nice envelopes, great editing features. You can use the SoundFonts that come with it, including a larger download that expands the raw wave data you can sythesize with. There are also some steps you can take to create your own soundfonts to use in Crystal. With the variety of sythesis techniques it makes available, and the ability to use custom soundfonts, it's very powerful indeed.

It is helpful and fun for teaching basic synthesis. What a lucky thing to discover Crystal. Enjoy!!