My 16 year old son is on LDN, he went on it August 2009, he started Hyperbaric oxygen at the same time, his CRP went from 48 down to 3 within 5 weeks and he gained 9 pounds, after stopping HBOT his LDN was compounded incorrectly (with Lactose) in Dec/Jan and he went through another flare where his CRP again rose to the 40's. We got the compounding fixed and he is now in remission, latest blood work showed normal CRP numbers again, he is also on SCD.
As with other drugs I believe it works for some and not for others, it was suggested to us when he first went on it to do a yeast treatment which we did with a natural product called Candacin.
Also, it is a good idea to start with a dose of 1.5 mg and work up to 4.5, the only side effect is some strange/vivid dreams. Some people feel worse on it at first before they feel better, but there are many Crohn's success stories using LDN. Your biggest problem with LDN may be finding a Dr. to prescribe it, or getting a GI to support you while you try it, ours was VERY skeptical at first, but I was the PITA mother who didn't take no for an answer - I figure the bigger medicines are still out there if LDN doesn't work (or quits working).
As for whether it's on par with Imuran etc, no probably not, because it works in a completely different way, ASA's try to control the inflammation, Imuran suppresses the immune system, LDN modulates the immune system, or tries to kick start the immune system to work appropriately, and to not over react.
Here is a link to an LDN yahoo group, you might find some answers there.