I've been seeing this issue too and it's seemingly getting worse. I'm not sure what the QNAP engineers are doing, but it should be pretty obvious of the delay's customers are seeing if they simply tested this in a lab. Seems to me every new firmware release packs more and more features into it without properly addressing base functionality of the product.
It' time this company started realizing that their target market is home and small business verticals of which apple products make up a significant portion of the computing base. Large companies don't use QNAP to run their storage services.... they favor companies such as EMC.
Ergo, QNAP had better start supporting it's base customers better or it will be another casualty in the technology arena. Hire some protocol analysts, get out the sniffers, and start core functionality better. It's AFP not bleeding edge science!!!