I've seen it before.
The only ones that I can imagine it would be comfortable to use are those odd, long ones that have a 45* bend in the middle. Otherwise, it would put weird angular strain on your wrists.
The main drawback that I can see is steering. You'll be putting your weight forward, and your leverage closer to the turning axis... Could get pretty twitchy.
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"I feel like my world was classier before I found cyclocross."
- Mandi M.