Follow the official advice from Kimberley. A small tent is fine, but remove it in the morning. Book in advance for meals and to let guardian know you'll be camping nearby (if they say no, don't - trust guardians know best. It won't be a financial decision for them: the sleeping money goes to the CAF, the one for meals to the guardian). At busy times there might not be room as there are limited bivvy spaces.
Positives: no snoring so potentially better night if you have good gear. Marginally cheaper (not much. It's meals that's the most expensive).
Negatives: the additional weight to carry is the main drawback. This year the amount of snow, you'd need gear to sleep on snow for all mountain huts as snow line below 2,500. None of the huts are currently reachable without snow gear.