As a logged in user, often I'm working alone on my own cakes. Sometimes I'll forget to claim a slice, and try to update it, which fails - asking me to take ownership.
Instead of failing and hassling me, I'd suggest allowing the edit - so long as no one else owns the slice.
Allow logged in users to update a slice *so long as there is no owner*
What is the point of ownership of the slices then?
The whole point of owning slices is for collaborative working.
Possibly an on/off switch for "Only owned slices can be edited"
It's very frustrating if you need to update a number of slices to a point, then release them.
If the user interface prevented you from editing a slice until you took ownership - by disabling the edit controls/siders/etc, that'd be fine - but it doesn't.
Instead, you edit a slice and interact with it, only to have your edit fail with an error: "You don't own this".
If no one else owns the slice, it's frustrating - you would expect the application to either automatically grant you ownership or not care about who owns it. I chose the latter approach.
Apart from that, Slice ownership still behaves as it currently does, so you can't upset other people by accident and have to vote or use admin mode to transfer it - that still offers the main value (Hey, Joe Smith is working on X!).