This was discussed in depth last year (see BEE-L LOG9602B).  A lot of
the decision process is a matter of preference and what works for you in
your area (so what else is new?).
 
I tried to do a comparison of the two last year, but unfortunately I had
a small sample size (only 1 hive producing Hogg Halves) using Killion's
methods, and after all the manipulations, the hive I put into HH production
did not accept the queen and I had to unite it with another hive.  This
is NOT attributed to HH equipment, just finicky bees.  But I was unable to
complete my comparision, which I will attempt again this year.
 
HH are definitely less labor intensive (no rings or foundation to futz with)
but it is my understanding that bees are reluctant to fill the corners
(although I have seen nicely filled sections).  I have been very satisfied
with consistant results using Ross ROunds, I hope to discover the same
with Hogg Halves, but so far my personal preference in this area leans towards
the Ross Rounds.
 
Aaron Morris - I think, therefore I bee!