Downsides of the Biodel formulations:

It's still an injectable - more discomfort, less discrete. Does it have to be refrigerated?

Injectable will necessarily have a slower absorption than inhaled. Also possibly a more variable absorption (scar tissue etc).

They are just starting P2 trials. Long, long ways to go. Must do P3 and then go through the entire approval process.

Just my take based on limted knowledge.