Yes, an applicant may file a Request for Reconsideration as well as an appeal. In terms of timing, it would be preferable to file the Request for Reconsideration earlier within the 6-month response period to see if a favorable outcome would occur before the 6-month deadline expired. If you wait too long and file a Request for Reconsideration close to the 6-month FOA deadline, the USPTO may not respond to your reconsideration request in time. Filing the reconsideration request earlier allows you to determine whether an appeal is still necessary.