Int eh early days, I used the jherb only until his foot grew out. Now I have him on it permanently. It's relatively inexpensive but if you decide to take her off, watch for changes in clinical signs: foot comfort, attitude, muscle or tendon issues.
You can probably do better with feed grade magnesium oxide, rather than the Remission, which, I agree, is expensive. Check with your feed stores or local feed mills. Should be $20.00 for a 40 pound bag which lasts forever.
Your salt should be higher too - two ounces by weight. Inexpensive insurance.
There are other things in your case history that could/should be eliminated for IR horses if you have not already done so. Thanks for providing the link. Really helps.
Nancy C in NH
ECIR Moderator 2003