Tried the round ones on various occasions, both on mills and lathes
and I wasn't very impressed. Problem is that its impossible to have
an optimum chipbreaker on a round insert so you are limited to free
cutting steels. I also found that I go only about two edges out of
each one due to fracturing. While they can flexibly cut in any
direction I feel that they are a specialty tool as they set a lower
limit to your edge radius.

From comments on this board and elsewhere there is little consensus on
the clamping issue. I like the center-hole cam-lock style but others
hate it.

The first tool I always reach for is a triangular insert . All the
others are for special situations.

I have a peeve with fancy boring bars when I crash the tool and the
seat breaks to protect the inset.

starbolin