We installed four of these in our historic B&B for two reasons. One, it does have the overflow protection. It was explained by the distributor that it's more of an overflow assist. the other reason is that it's a dual flush toilet. You lift up for number one and push down for the conventional flush for number two. There were other dual flush commodes like Geberit and Toto but this was the only one with the overflow and was a lot less expensive.
For those in the States, the national distributor has them at great prices. The reason is that Lowes, the big box home improvement chain, cancelled their purchases because they weren't selling well so now they have plenty available..