I would like to convey my limited experience in the Northeastern U.S.
with the Swedish polystyrene miller type feeder that Mr. Gustafson referred
to in his email.  We have used several for a season and a half, both on
wooden and polystyrene hives. We first started two new packages in
polystyrene hives with new, unwaxed Pierco Frames. , one with the Miller
feeder and one with the  two gallon pail feeder on the 21st of April.  The
bees took about twice as much feed from the miller feeder as they did from
the pail feeder and started drawing the ninth and tenth frame about ten days
earlier. I doubt that the results would have been as different had the bees
been in wooden hives. The nights in late April and early May are almost all
below freezing here and the cluster would be much tighter in a wooden hive,
although as Mr. Gustafson indicates, the feeder serves as an insulated top.
This fall we used the polystyrene feeders to add a second story of empty
drawn comb to some one story hives in late October.  The hives took down
about 60 lbs. of high fructose corn syrup by December 1. The interesting
thing about the feeders is that there were still bees feeding in the
polystyrene feeder when the early morning temperature was down to 15f. Next
Spring, we will see if the same thing is true in early Spring.  Personally,
the idea of having a feeder that doubles as a winter top insulation device
really appeals to me. No more hauling pails back and forth and washing them.
We did however remove the Plexiglas cover on the feeding area of the feeder
before winter.  We reasoned that although the polystyrene will let moisture
pass, the moisture would take the path of least resistance through the hole
under the Plexiglas feeding plate. It would then hit the Plexiglas and
condense on the front of the top bars.  Mr. Gustafson might want to comment
on whether he does this or not to his feeders before winter.   We sold about
500 of these feeders in the U.S. and would appreciate feedback from other
users.  They are certainly more expensive than pail feeders, but if handled
carefully, they should never leak because they are one-piece molded and
should pay for themselves in a year or two in decreased labor costs and
better wintering and thus stronger hives and more honey production
Incidentally, the package hive that we used it on in April produced a whole
medium more than the one fed with the pail feeder. For Sale, 500 dirty two
gallon pail feeders, cheap!  We will not be importing the Swedish feeder
this year. It is designed to fit  the polystyrene hive, and although it
could still be used on the wooden hives with no problem, the wooden
telescope covers had to sit on top rather then over the feeder.  The new
BEEMAX feeder will be out in early March and will be sized for the wooden
hives, although, of course, it can still be used on polystyrene hives.
Happy New Year Bob Stevens