I've never had to deal with Asus RMA before, personally. Technical quality appears to vary a little from region to region. Service quality (customer support and RMA approval response) appears to be entirely inconsistent from region to region.
But I suspect they'll ensure any cards they service and rebuild will comprehensively pass every test they can possibly perform, to be personally inspected and checked and rechecked in finest detail. It costs Asus too much in labour and shipping charges (and lost revenue from dissatisfied customers) to gamble with substandard product output. So I suspect your unit will not be worse than a random QC piece from the factory.
You'd think they'd give you a few ROG stickers or something to apologize for any inconvenience, lol.