500 separate paths or shapes is the maximum allowed when copying and pasting editable paths from Illustrator into InDesign. If a set of paths is too complex, ID will place the paths as an embedded EPS rather than editable vectors. When using Illustrator’s Live Trace feature, pay attention to the number of paths listed in the lower right just below the Preview button (number of anchor points is irrelevant…ID isn’t looking at those). 501 or higher will get embedded as an EPS. When you plan to copy and paste into ID, 500 is the magic number.
Thanks to Tim Cole for this tip.