NoFrost isn't just marketing - the system actually works. But whether it's worth paying twice as much really depends on your patience. If defrosting an old Biryusa is just a chore you do once every six months to a year and you don't stress about it, then there's no point overpaying. Your fridge will keep running for 10+ more years anyway, and you'll just waste extra money.
But here's the thing: if your kitchen has high humidity, you're constantly opening the freezer door, or you live somewhere with temperature swings, then ice builds up fast and heavy. In that case NoFrost actually makes life easier - the ice layer grows slower, the cold stays more stable, the compressor doesn't work as hard. Don't believe the hype about "years without defrosting," but once a year instead of twice? That's legit.
Practical tip: before you fork out the cash, check if your current Biryusa can still last another couple of years at least. If it'll run longer than you'd be paying for the price difference between a basic model and a NoFrost one, wait it out. And when you do pick a new one, don't just look at whether it has the system - check the freezer capacity too. NoFrost models often come with a bigger freezing compartment, which can actually be more useful than the system itself.