I have looked at the BLT307 case, but it is a bit larger than both the BM307 (the "micro-" case that the OP refers to, and the MX307 (Protec MAX...I have a couple of these, larger than the BM, but smaller than the BLT). They are all nice cases, and offer reasonably protective cases in small form factor. I cut of the zipper guard 'flap' and the backpack clips on my MAX cases, but do find the two outer zipped pockets to be occasional useful; they are designed to add minimal thickness when empty.
For everyday use, I have been using the SKB Clarinet Case...no nonsense solid case from a long-term instrument case supplier.