It takes some getting used to, thats all. It does work and just fine for me.
Separate the brake pedals, select your gear range, set your throttle, move the cruise lever with your left hand and steering wheel with your right. To turn, use the steering wheel (if the front wheels are in ground contact) and press an appropriate single brake pedal with your right foot. You can rest your foot on the hydro pedal, it will be rigid once you move the cruise control lever. Your left foot is not used, so even a one legged tractor owner can comfortably use these turning brakes when he is not busy competing at the local **** kicking contest.
It will return the cruise lever to the off position (or very close) when you step on both brake pedals together. Will scare the feces out of you when you expect to stop by pressing only one brake pedal and this machine will do a lot of damage very quickly so get used to the cruise lever in a wide open area before working close to anything. You are correct that reverse is not available when using cruise. It will soon all become second nature.
All this is well explained in the manual but becomes much clearer when attempted.
When I snowplow with mine the front wheels are usually in the air so I think the turning brakes are a great feature. I must say this though, the front wheels in the air make 4WD fairly meaningless.
All the best,
Martin