I've seen the Koga up close and it's incredibly built and strong. My Jamis Aurora or the Trek 520 look skinny and weak compared to that bike.

As for the headset, there's a couple doing a trip around the world, developed problems with their headset and could not find anyone to fix it. I don't know where they are located but that headset can be fixed by any bike shop here in my town. I sent an email to Koga on this headset and they said something to the effect that a competent bike shop would be able to fix it. I had a couple of threaded headset fixed over the years and it's not has hard as one would think but experience will make the difference.

There's more to that story and I read they were hoping Koga would give them new bikes after all the promotion or a larger cut for bikes they sold. When this didn't happen, everything went downhill afterward.

This couple did a lot of damage to the Koga brand and the headset "Problem" has become a reality in people's minds more than anything else. I suspect it must have cost Koga thousands in lost sales and it would be in their best interest to resolve this issue.