I've just completed a feature branch and merged the branch back into the trunk. Should I now delete my current working copy and checkout a fresh new copy when I'm ready to work on the next branch?
I would think this is a yes or it's up to you because I may want to checkout completely different files next time.
By defintion of a feature branch - I would delete the working copy. But you can as well
switch
to a different one, when you start working on another.