We have one, and soon we will be getting a second exterior lift-sliding door.
I like them because the sliding doors are out of the way – easy to use, but every now and then I think about the fact that a brushed system can't insulate well.
Although I have read that they are very tight now. I'd be interested in comparing the insulating effect of the lift-and-slide and "regular" doors.
Does anyone know where to find the information?
We have a rubber seal. It is airtight, at least according to the airtightness test for passive houses. After 3 years, no drafts.
I looked closely at the procedure for the door and am pleasantly surprised at the sensible idea:
When the door is raised, it lifts off the top of the rail with a tapered section (it can be moved) and when lowered, that gap closes again. At least the air exchange is reliably prevented this way.
I think it works, the system (the brush seal is not an actual seal, but probably helps in particular against dust and insects)