I have owned one Dr which I toured 12 k kms around New Zealand on. I also ridden a Dr around 5 k kms in Bolivia. The Cb500x I have rented in Thailand and I did around 2500 kms on it, it was the standard version, not the RR.

The Dr are by many considered the best travel bike ever. Its lightweight (under 150 kilos dry) its almost bulletproof and very well suited as a travel bike. However it does need many mods to get its potential out, such as a bigger fuel tank, suspension upgrade, seat upgrade, etc etc. It will not do anything great but it will do all reasonably well.

The Cb500x - is also a good bike for what it is. Its a Honda and by that almost bulletproof, it has amazing fuel consumption, and with the RR kit its probably halfdecent on gravel roads. But with the RR kit its not cheap anymore. Its also quite heavy for what it is. I only found the wet weight for it right now which is 195 kilos, so probably around 180 kilos dry. And that is more than 30 kilos more than the Dr. And when going off tarmac we all know the 3 most important things is weight, weight and weight. So with that in mind the Dr would definetively be better off tarmac. But on tarmac the 500X would be the better imo.

So it comes down to what priorities you have, will you spend much time off tarmac? Or on tarmac? What other things are important for you? Fuel milage and costs?
You probably wont go wrong with any of those bikes, its just a matter of what prioities you have and what features that you find important in a travel bike.

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In the end everything will be fine. If its not fine its not the end....