These are just my impressions. I'm glad that there are so many fans of a new alternative operating systems!
MorphOS is asking for a serious sum of money so I expected more. At the time I installed everything was not as polished as other operating systems such as BeOS. The user interface and stability all looked hobby OS to me. Again, this may have been before the 2.xx series really took off so the situation may have improved.
Partition encryption does not equal encrypting your boot drive. If the spooks or other criminals can log in it's game over.
The OWB failed to deliver a good enough experience loading and displaying web pages. Again, this may have been an earlier version. Also, we're talking about user experience so I don't care if it's flash performance is the same on Linux - it sucked.
Finally, with Mac OS or Windows I can stick in my OS CD and install the OS on any machine I have. I don't need to prove to ANYONE my machine is broken. I don't care if Mac Minis don't break that often. It's MY choice when and where to install Mac OS. With MorphOS I need to "prove" it's broken. Not good.
..and to make it clear I object to ANY form of activation on any other platform. Activation is wrong by principle. I bought a piece of property not a license.
Despite my less optimistic review than the OP I would QUICKY snatch up MorphOS if it had:
* No activation. I own the software.
* User/Password security. No one should access my files but ME.
* Full boot disk encryption. Same deal.
Again, this is just my experience with an early 2.xx revision. I didn't mean to get into a point-by-point debate. just thought I'd clarify a bit!
Carry on 
Is full boot disk encrytion really all that big of a game changer for an aternative/hobby OS?
We only use that at work for machines that leave the building. I'd say about 1 out of 10 of them end up becoming unbootable because of the encryption software.
