I have about 1800 hours and I would say that 80% of
my flying is from winch launching.

My club operates primarily from the winch launch. When
our club was a bit busier we completed anything up
to 120 winch launches a day.

Winch launching, like anything in flying, is completely
safe if people are trained properly. I am not going
to teach people how to winch launch over the internet
but I will say that the number one rule is never to
get yourself into a situation from which you can not
recover with the energy (whether kinetic or potential)
you have. Put simply - never climb steeply from the
ground, always maintain an shallow 'initial' climb
until you reach a safe height and speed.

Winch launching is more Labour intensive than aerotowing
as you need a winch-driver, a cable retrieve driver,
a competent and experienced person making the decisions
and supervising and a wingrunner. However, for a training
environment it is certainly much, much cheaper and
fosters a 'club' atmosphere as everyone relies on eachother
to make things happen.

I do not know any statistics of winching vs. aerotowing
and frankly I think that statistics are, in general,
irrelevant in gliding (just look at the US contest
finish stats, I counted 4 in the last 17 years but
people think this is an area out of control in the
US). But what I do know is that I have never been in
a situation where I could not land safely on the airfield
in the event of a launch failure and I have never just
cleared the boundary hedge by a matter of inches (my
gratitude to the tug pilot for not dumping me has been
expressed many times in the form of beer) in a Duo
full of water on a winch launch either.

Having said that,I also feel that aerotows are also
safe when given that the equipment is regularly inspected
(whether it be the tug or rope) and that the landing
options are fully researched/explained prior to take
off. I have never not considered an aerotow because
I felt it was unsafe.

I guess my point is that both types are utterly safe
if people are trained and have a plan if things go
wrong, again like most situations in flying.