Is there any research that shows palliative care is beneficial?

Yes. Research shows that palliative care and its many components are beneficial to patient and family health and well-being. A number of studies in recent years have shown that patients who have their symptoms controlled and are able to communicate their emotional needs have a better experience with their medical care. Their quality of life and physical symptoms improve. 
In addition, the Institute of Medicine 2007 report Cancer Care for the Whole Patient cites many studies that show patients are less able to adhere to their treatment and manage their illness and health when physical and emotional problems are present. To view this report, go to http://www.iom.edu/Reports/2007/Cancer-Care-for-the-Whole-Patient-Meeting-Psychosocial-Health-Needs.aspx 
Furthermore, patients who have serious illnesses and receive palliative care consultations have lower hospital costs than those who don’t. These consultations help determine treatment priorities and, therefore, help patients avoid unnecessary tests and procedures. (For more information, go to http://www.cancer.gov/ncicancerbulletin/NCI_Cancer_Bulletin_090908/page3 )