The real problem is the Suzuki is a close ratio gear ratios too. There is actually a company, ACT, making a wide ratio gear set for the DRz/KLX400. Wheeling Cycle carries them. Low first with higher top gear. The power range of the 400 makes it work. Smaller bikes need more gears to do the job due to lower power.

I rode a 7 speed Hercules 250GS Six Days style true enduro back in 1984 or so. We had taken one on trade. The true answer to a dual sport with excellent capabilities. The thing was walking speed for gnarly tight woods stuff in first and readily capable of triple digits in seventh. It would be awesome if one of the makers did it to their 250 dual sport. Just think what it's like running the 13/42 or 13/42, getting into sixth gear, but then there's still one more! It would make the bike far more "adventure" capable, being geared to deal with the load on trails, yet still be able to run 65 without screaming.

I think the Six Days now requires max six speed, but that's irrelevant. Kawasaki ignored race requirements over the years with their ZX6. Seems they made like a few hundred ZX6RRs that met the 600cc limit for racing - but for the street they made the ZX6R, which is 636cc and it was and probably with it coming back again, still the king of mid size super sports power. Of course there is the obvious reason why, but on the street there is no limitation. Same could happen with a 7 speed dual sport - there is no law against it, it's not racing. Plus it would be fun. I love rowing the gear box.