Hi List;
I had a butternut up about 10 years ago so there may have been some changes
but one big advantage is that the antenna could be tuned or retuned from the
base.  If you are considering mounting it on a low roof, they offer a set of
tuned radials.  I am using a r8 and the problem was that in order to retune
the 40 meter section which was rather narrow you had to take down the
antenna.  If it was mounted on the ground this wouldn't have been such an
adventure.  Since it is on the roof of my two story house, however, taking
down was a bit of a bother.
Take a look at the gap antennas.  If this one dies I may take a look at gap
when I put up my next antenna.
Rich