I am delighted to say that I have been successfully "migrated" from long term IB to the ESA Support Group. Although I filled in the ESA50 form in great detail, added numerous extra pages and very supportive letters from doctors, I did have to have a medical, so the eventual outcome was a huge relief. Also, I sent for my ESA85a and was enormously pleased to find that length of time before reassessment is "in the longer term".
A very big thank you to Steve's documents, all the moderators and members of this wonderful website without whom my "migration" would have been so very much more stressful.