Would CiviCRM be appropriate for a 501(c)(3) medical group practice's philanthropic endeavors?
Without knowing what your organization is trying to do, it is difficult to provide meaningful feedback. You should take a look at CiviCRM's features and see if it fits your need. At the bottom of the site you'll find some useful links, including:
Browse case studies, Contact an ambassador, Introductory webinars, Watch videos, Try a demo, Read documentation, Ask a question, Find an expert
If you are needing to track/administer contacts, organizations, contact relationships and outgoing grants, then yes, CiviCRM would suit your organization quite well.
See this link for the grant component: What is CiviGrant?