I just began the remicade/imuran combo myself. I found an article published by the mayo clinic on the combination, titled "Mayo Clinic: Two Drug Combo Twice as Effective for Crohn's Disease remission"
And here's an excerpt from it:
[in regards to a study done which found great benefit from using the drugs in combination] "These study results are strong enough to change clinical practice," says William Sandborn, M.D., gastroenterologist and vice chair of the Division of Gastroenterology & Hepatology, Mayo Clinic, Rochester. "They have certainly changed mine."
Although i have no history yet to speak of, I found consolation in knowing my dr was prescribing something that one of the world's leading medical research teams ( THE Mayo Clinic) recommended, and I hope it brings you some peace of mind as well.