Will the zips leak?

The zips are covered by dual flaps.

In poncho mode any water that creeps past these flaps is well away from the body and isn’t usually a problem.

In bivibag mode make sure that the zips are low and to the side and that the flaps don’t form a gutter to direct water inside. In very wet and windy conditions it may be prudent to sleep with the zips almost below you: A sleeping mat will prevent water penetration. Silicon sealer can be applied to the zip seams if you intend using the ShellTA as a bivibag in very wet weather.

In mountain shelter mode most people will be wearing a water resistant jacket inside and small amounts of rain coming through the zip will not be a real problem.