Cold Weather PreHeating

Now that winter has finally arrived in the Northeast, it is time to enjoy
the benefits of cold, dense air. wow - I wish I could see those climb rates
in August.

But anyway, what's the common wisdom on preheating. Granted, in an ideal
world, preheating is probably a good idea anytime it's below 40, but it IS a
pain for those of us who are forced to tie down outside and have no access
to electricity. At what temperature point are you comfortable starting
WITHOUT a preheat? (If it matters, this is for a Lyc IO360 that will start
easily down to about 10 deg).

Any mechanics care to comment on what they have seen happen to engines which
have routinely been started cold?