Of the two models you name, I'd go with the 5G, regardless of the hours. I say this because the K is going to have a Tier 3, C4.4 ACERT engine, which means computer controls, and if I'm not mistaken, a common rail fuel system. The G model has a Tier 2, 3046 engine which has a more conventional injection system.
In my experience, the conventional injection systems are going to be the easiest to maintain, and are far more tolerant of variances in fuel quality, which I would expect to be an issue in your area.
Between that, and the maintenance issues involved with the computer controlled systems, again, I'd have to choose the G over the K any day of the week.
That said, you could probably get an older D6D with a tried and true, completely mechanical, Tier nothing, genuine 3306 CAT engine for far less than the cost of one of either of the machines you mention. Weight wise they are almost identical, but you'd gain nearly 40 HP with the D6. Too, you'd gain the ability to access far more aftermarket parts for both the machine itself, as well as the engine.
The link below is a comparison of the two models, with the exception that the 5 is a LGP model. I imagine with the standard pads even the ground pressure would be nearly the same between the 5 and the 6.
As a field mechanic by trade, if I was in the same local as you are, I would much rather have the simplicity of the 6 to deal with come repair time, as I had the complexities of either of the 5's, or any newer machine for that matter.
Hope this helps. Wayne
Richie specs