At the risk of backseat designing, it seems that all that is really necessary is the ability to provide a list of labels and not specify how they are displayed. One would think that by default it would just load whatever is set to be the default with minimal prompting unless a key is hit. This is similar to how GRUB is usually set up and how I think Mac's work right now.
While it may be do-able to load modules for common filesystem types, as GRUB already does, so you can load kernels off them it seems more productive to be able to EFI boot the kernel directly and have the current and previous kernel images live on the EFI system partition. Basically make the EFI system partition replace the /boot directory.