Well, I have Dreaded 3, Respectable 13 and Bizarre 4. Most of the Bizarre comes from items, while Dreaded and Respectable are from Expanded Inventory section (most of the items there give Respectable). I had little trouble getting the map, I just had to take my chances a few times before succeding. So if you don't mind the loss of items, go for it.
EDIT: Forgot the point of the post, silly me. I wanted to say that I succeded on Impossible and High Risk challenge to continue, so you should probably keep trying to get it, it's not really that hard to obtain the required stuff.