If you're mainly riding in Oz then a board like the T.Rice is a waste because there aren't really many good long runs, POW, or decent off piste areas (in comparison to most places in the northern hemisphere at least). For your weight 157 is going to be better than the 161, sure you lose a bit of effective edge but it's going to be a lot more fun to ride on and hit small park features. Board sizing is more closely related to weight than height, so a 161 for your weight is going to be very stiff. I'm 70ish kg's and ride a 151.5cm.
Most companies do a board like the Burton Custom Flying V (A good all-mtn mid-flexing board hybrid camber/rocker design) which would probably be more suited to your style of riding and Australian conditions. GNU Riders Choice, Never Summer SL off the top of my head, but look around. Of what you listed the Ride Machete is the best choice for you IMO.