First, check valves should never be used in a SW tank. The different creatures growing on the LR will also grow on the valve seat, preventing it from closing properly no matter how often you clean them. A properly designed setup should have enough sump capacity to handle all the water that drains out of the setup without overflowing the sump.
Second, the use of siphon break holes is a band aide fix. If you place the returns at the water surface instead of under it they will pull air almost as soon as the return pump is turned off. What little water they do pull should be handled as described above.
BTW, the Durso is only used on the drains, it isn't part of the return plumbing. It was created to eliminate the waterfall effect of water falling into the overflow box. There are several newer methods that handle more flow with less noise but they are a little more complex.
HTH,