Yes things like shipping back to a factory in China for warranty work which can cost half the price of the item. JDS or Schiit are just post office rates without customs and the rest to go through. I used to buy thinking my credit card would double the warranty, until I read the fine print. It's only if I get a repair estimate first from an authorized service center. For Topping or SMSL they don't have any of those here in the U.S. for out of warranty repairs. Even Hifiman will just offer 20 percent off a new pair (if you send them the broken one, you pay shipping), but they won't repair many models aren't in production. Allstate has the Squaretrade warranty you can buy, but it's expensive and if you've seen their horrendous feedback rating, it's not that likely they'll handle it well.Actually, you might also want to think about the other differences, from warranty and support through build quality, features and ergonomics, as well. In fact, with electronics, those may be more important, and more obvious.
I'm buying and selling audio equipment all the time, and there's some models I won't touch anymore. The number of "parts only not working" Drop THX 789 is madness. I know they sold a lot of them, but never seen so many listed in protection mode on eBay. After the Topping L30 recall debacle where dealers were asking people to smash them with a hammer and send in a picture of it...omg. JDS Labs is worth it just for the support...