I've been enjoying the various discussions that are going on, and
particularly appreciating some of the posts from newcomers and some
who have been here for a while, but not said much.
 
I've fed 2:1 (and more dilute) sugar syrup all winter long, many
years ago.  Others have doen so too.
 
I can't say that I noticed any moisture effects at all.  As far as
dysentary is concerned, I saw no unusual levels.
 
What I did see was that the bees just did not amount to much in the
spring - and I attribute that to several things:
 
For one, I wouldn't have been feeding if the bees were well fed in
the fall.  Thus I presume that the bees may not have had an opportunity
to raise the high quality bees that are necessary for overwintering.
 
Second, there was no - or little - feed to cover pollen stores that
are absolutely necessary to have good spring buildup.  They ate their
pollen earlier on, when it did possibly more harm than good.
 
Third, consuming sugar syrup (sucrose) is hard on bees - it ages
them, I'm told.  Honey stores would have been better.
 
Fourth, as Eric pointed out, feed provides a heat reservoir to help
moderate the hive temperature furing winter
 
Fifth,  the combination of feeding and lack of honey in the combs
tends to stimulate undesirable flying and consequent dwindling.
 
These observations are true for my area, and as a result, YMMV.
 
As far a fermentation and such is concerned, I have to say that
my observations are that a good hive of good bees in the spring and
summer can handle a fair bit of fermentation with no apparent ill
effects.
 
On the other hand, I suspect that it may be a stressor and could be
lethal if accompanied by other stress factors.
 
My approach to beekeeping has changed over the years.
 
In a nutshell, I guess this is where my thinking is today:
 
There are many environmental factors that can be regarded as
beneficial forces - or their opposite, stressors.
 
Bees condition, performance, and survival depends on the balance
between these factors.  Few stressors alone are lethal, but given a
dearth of beneficial forces (I need a better name here), they may
gain influence.
 
A list of stressors would include:
 
AFB, EFB, chalkbrood, sacbrood, septicemia, paralysis, nosema, etc.
Mites,
Excessive and continuing dampness
Cold winds and low temperatures
Predators
Mice
Lack (or excess) of ventillation
Lack (or excess) of space
Shortage of feed near the cluster
Toxic or contaminated feed (honey, syrup, or pollen)
Poorly balanced nutrition
Unbalance of population age demographics or lack of population
Clumsy and inept management by the beekeeper
Add you favourite bane here. . .
 
A list of beneficial forces includes:
 
Honey flow (the best)
Warm dry weather
Long days (June 21st around here)
Medication - if appropriate
Feeding (as a substitute for a flow)
Add your favourite here. . .
 
As you can see, the list of stressors is long, the list of helpers is
short - if we leave out the negatives of the previous list.
 
When these stressors gang up on a hive, then we see results that we
ofen blame on the most obvious agent.
 
Nonetheless, it is my experience ands that usually there are several
factors combining to cause illness or death of a colony.
 
In my opinion, the factor that is most often responsible at some
point in the chain of events is starvation.
 
Shortage of an essential food at some point during the year weakens
bees for quite some time after, leading to conditions that are bad
for the beekeeper and worse for the bees.
 
At risk of sounding like someone offering a panacea, I must say that
feeding bees spring and fall is essential in our area to get the
best out of them.
 
When bees are well fed, a lot of the other problems tend to fade back
a bit.
 
The more a beekeeper can do to increase the good influences and manage
the stressors, the better the bees will do.
 
I'd like to see what others can add to the lists above.
 
And to answer Kelly's question from my perspective:  Consider the
other stressors bearing on the bees at the time  when you give them
the supers.  If other factors are favourable, then don't worry.
 
They can bear a certain load of stress with absolutely no bad effects
(a honey flow is a stress in that it wers the bees out, but the good
effects far outweigh the bad).  But when the stresses add up to a
certain point, the hive strarts a downward spiral.
 
And in regards some other postings:
 
 >Some beekeepers here persists to use strains of ligustica bees that
 end up
> >in a mess each spring with wet and mouldy frames and lots of dead
> >bees.
 
<snip>
 
>.We have some ligustica (Italian) in our bees
> and they winter well.
 
FWIW we have lots of Italians that winter very well, but one year we
bought 100 packages of New Zealand Italians and they nearly all
perished the first winter - while other hives wintered normally, so I
guess it depends on the italian strain.  They were also the yellowest
and most vicious bees I ever worked in all my years.
 
In defence of NZ, I am sure all their bees are not like that.