Save as much money as possible and buy two CRF250 Rally's or CRF250L's. Benefits include:
Same parts
Reliable
Slower = Safer - speed does kill, don't underestimate the value of this.
Doesn't chow parts like crazy (tyres, chains, sprockets)
Light on Fuel
Long service intervals
Bikes are light so sandy terrain is easier
I'd guess two of the CRF250L's would be a better option. Also you wife would be chuffed that you have the same bike as her. Fuel range is the only downside but you can carry extra fuel in a rotopax.