However, I understand it uses a resonator rather than a crystal, and that may be a problem for what I will use it for.
As you can read so far oscillator accuracy and variation can be quite a complex subject and matching a solution to your requirement can range from easy and cheap to quite expensive.
Have you done any math to find out what your actual timing accuracy needs are? Over kill can be a waste if the problem exists only in your mind. 
Lefty