To be fair any AT regardless of type should always be locked into a low gear in a Manual mode for off road use. Even ramp launching boats on pavement should always be a manually selected gear to be held till you indicate otherwise.Can't get a manual turbo Forester in the new model, or the outgoing one. In fact the new Forester turbos only come with a CVT now. The last gen turbo only came with the 4 speed auto. Subaru was out to sell cars, not make interesting ones.
And you're right, the CVT is NOT great in sand, at least not in the 2011 Outback 2.5i when left to do its own thing. I've driven a good chunk in sand, and leaving it in fully auto mode is not advisable. In full auto when you let off the gas it slips the ratio to a more fuel economy friendly one, then the car bogs down in deep sand. Keep it in "manual" and shift with the paddles to keep the rpms high and the car moving. Lock the ratio in "1" and let 'er rip. Not a problem, really.
Running any AT in standard Drive AT mode when off road is a Rookie mistake and will cause you problems.