IGH means symmetrical wheel. Dishing is a weak point - the shorter drive side spokes on a dished wheel are more prone to snapping.*
Belt drive I don't know about. They don't like swallowing stones into the rear sprocket - this snaps belts. If you look at a belt drive Harley motorbike you'll see that the rear sprocket is shrouded for this reason.
*Ironically - Mark Beaumont, on a recent successful around the world record ride, had problems with a Rohloff carrying wheel. The wheel was built completely with spokes shortened by the mechanic (as opposed to using manufacturers spokes of the correct length). Shortening spokes is a good trick for mechs like me who carry spoke stock of one length - and use shortened ones as a replacement for one or two spokes on a wheel - not the whole lot.
Anyhow, belt drive - simple - but, as with car motor cam belts - replace them regularly.