ONLY if one end of the board begins or eventually is not in contact with
the
blade during the entire cut.

If the board is relatively short, too short to go through a jointer to
straighten, and will remain in contact with the fence through the entire
cut
the pricedure would benefit from the a longer fence as the piece would
travel in a straight line.
Lets say we have a 30" deep saw bench, with say a fence of matching
length running a 12"blade running at full height. You would only have approx
9" clear of the front of the blade which would mean you could have a maximum
of a 9" piece of timber remain in full contact with fence. I don't know
about you but it would be very rare for me to be working with such short
pieces of timber.
When I commented I was referring to ripping long lengths of stock. The
two types of fence are designed for 2 different purposes. A short fence is
designed for ripping rough stock and a long fence is primarily designed for
cutting panel stock.

Actually I have had to guard against more "starts of a kick back" with an
under powered saw. With my cabinet saw and regular kerf blade the blade
seldom shows any sign of binding as the saw has the power to power through
the cut. In my experience the more HP the safer all cuts are.
I agree totally about more power the safer. Its like the sharper a
tool/knife the less dangerous it is. But the reality is that a majority of
saw benches sold aimed at the domestic market are usually underpowered for
the size they are capable of cutting.

The reason we are seeing some confusion about fences is because
manufacturers are trying to make one machine more versatile and do two jobs,
Anything designed to do 2 jobs only ever does half a job of each job.
If you look at the sliding tables on saw benches (European design I
believe there are refereed to as) and full length fences which is primarily
designed for panel work. The table is usually of too short a travel for
sheet work and the rigidity of the guide rails is usually questionable. A
true panel saw is set up so the bed travels right next to the blade and all
the weight of the sheet is on the travelling bed. On most of these European
style saw benches their is usually about 12" of fixed bench top between the
traveling bed and blade. However, the sliding fence is a big improvement in
safety over the mitre guide when it comes to cross cutting normal stock. I
hate mitre guides they have no 'secure' attachment to the bench. Something
goes wrong ant they rip straight out of your hand and the saw bench.
Ripping of rough stock is always done on a short fence. Take a trip to a
local mill and have a look how they have their fences set. Front of fence
will be in line with gullet just above the thickness of the stock being
ripped. Although you will find most operators are not religious about this
setup, but their setup will be close. In the real world you cant change
setup all the time for minor variations. You will also find that the fence
is set with a slight lead in. Once the stock has been cut by the teeth there
is no reason for it to be guided by a fence any further. The saw blade and
riving knife take over this job from there. Sawing green rough stock on a
full length fence will generally cause no end of problems with jamming.
Stable, seasoned dressed timber will usually rip OK with a full fence.
However if it is under stress as bowed timbers are it will tend to jamb when
the stress is relieved by the sawcut.

I appoligise if my words seem bit strong at times but coming from a trade
background using "Real" machines and seeing some horific accidents over the
years, I have some very strong views about the safety of machinery designed
for the small workshop/domestic market. I have a great respect for a lot of
ppl in here and have seen some very ingenious ideas and some very exqissite
work, but on the other hand I have seen a lot of sugestions on very
dangerous ways of doing things. Just as I would be totally lost if I lost a
part of my anatomy and not able to do what i enjoy most, I feel you would be
the same.