That's my perception too.I would say no. It is just that there are a ton more of them out there and they are marketed toward the DIY crowd so you just hear more about the issues.
For example, I think the two 8" ducts on the Tundra give the appearance that you just connect them somewhere convenient and expect it to work fine, but adequate ducting isn't necessarily that troublefree with any furnace. I think that the large plenum on the Kuuma makes people put more effort into properly connecting ductwork, even though the same principles are involved. Maybe that's just my perception.
SBI offers good customer service too, although Kuuma sounds like they have a more personal and see-you-through-it interaction.