Age old dilema. Space, weight, fragility, convenience. And how that affects the ultimate result.
I've used the D70, but have no idea how tough they are. Packing it in a smart place is the key. Quality foam is what I use. Yes, takes up valuable space, but what can you do? A little pocket cam with a plastic lens? In fact, that is what most riders use.
I have a Canon 20D but rarely use it because I'm afraid to ruin it and its big.
But next trip I'm biting the bullet, buying another lens for it and taking it.
If the specs on the 18-200mm are good enough, I'd go with that. The kit lens on the canon is not great. I'm thinking of a Sigma 17-200mm myself for the 20D. I'd love to take a super wide angle too but good ones cost an arm and leg. But they are small and easy to pack.
I've owned and traveled with many cameras, lately all small digital ones.
For years I traveled with a Nikon F2 (then F3) film camera. Big, heavy but
bulletproof.
Then I got a Canon G3, then A520, (broke both of them riding dirt). My latest small digital is a Panasonic Lumix DMC FX-8. I got it for around $250
and the quality is good. The bonus with this type of camera is the Super Zoom. The lens zooms to 432mm !!!
The new version of this camera goes a bit wider...28mm instead of the current 35mm I believe. That is the one drawback....35mm is really about
50mm....so I need a wider lens.
On my last trip the Lumix did well. I am not yet fast with it yet....just takes time and practise, but its OK for the price....really expendable in a way. It is small but not small enough. Its like a miniature 35mm Digi SLR. The lens sticks out the front. Still, not bad.
I did a two week Baja ride, mostly all rough dirt and the camera did just fine.
I would buy the best lens you can afford, and don't forget some filters....ND,
polarizer ect.
Packing it all is the tough part. Good luck.
Patrick