If you live in a climate where snow buildup is common (certainly the case where I live), maintaining a hedge can be quite a hassle. Snow tends to accumulate on top in the winter and pulls the branches downward on either side, destroying its symmetry. And in spring, no amount of pruning, staking and cajoling ever seems to fix the damage. As a result, I see many gardeners out there in the late fall tying the hedge together with twine, wrapping it tightly in burlap or even building a wooden cage around it so it can resist the weight of the snow to come.
Yet there is an easy way of preventing this kind of damage: simply prune the hedge so it sheds snow rather than accumulates it.
Forget a flat top: it may look great, but it gives you a hedge that is designed to fail in snowy climates.
Instead, give the hedge a rounded or triangular top and snow will slide off without damage.
Leave flat-topped hedges to those who live in California, St. Tropez or elsewhere there is never any serious snow buildup. In snowy climates, be a laidback gardener and prune your hedge so it’s adapted to local conditions.
Or be even more laidback, and put in a no-prune informal hedge!
Your suggestion of an informal hedge also allows flowering to occur. Of course it also entails selecting a plant that is small enough for the area.