Soft is a lot easier and faster to use in my opinion.
The only trouble is it doesn't last as long.
It's more prone to cutting, and goes "blunt" on the edges quicker.
Hard is the opposite.
Tougher, but harder to work with.
What I do is use soft and cut it a bit too long.
Then when it rounds off I cut the ends by a few millimetres and it's a sharp edge for a few more days.
