[JJMcJ]

Wouldn't the air above the water tend to hold the water in the bowl, since emptying the bowl would create a partial vacuum? And would that effect, if it exists, be enough to prevent effective flushing?

[goodpoint]

If anything it would really help avoiding clogging. Perhaps you can even get rid of the water reservoir and use pumped water instead.

The lid could be transparent to make sure no surprises are left behind.

[chopin]

Water in = water out. This shouldn't be much of a problem.