Apple - Is there a practical ePub book reader program for Mac OS X?

I haven't used it - so I can't say if it's any good - but I noticed that you didn't include the Barnes & Noble app in your list. Have you tried using that to view your ePub books?

BookReader

I can't vouch for this guy because I haven't bought it yet. But you might want to try this app store variant if your willing to spend a little money. Price is usually $10, but it appears to be on sale right now.

It supports 10.7 Lion, gestures, and appears to be well supported.

Ehon is intended to manage comic books and ePub and is available on the Mac App Store. (It used to be paid, now is free)

It seems a bit buggy though and to me, the Nook software might be a better choice.