I would say any large change to a tank, especially moving, will cause some die off and a "mini" cycle. Its true that your bacteria form mostly on the live rock, but something as traumatic as removing the sand bed, and thus all beneficial organisms therein will cause some disturbance. Not to say you won't be fine though. Its been done before. My advice would be to only do half (unless you have crushed coral). Saves money too, as you would have to buy only half as much live sand. I wouldn't recommend rinsing live sand either, as you'd rinse out a lot of the beneficial organisms. Expect an algae bloom, and an ammonia spike, but nothing as extreme as when you first cycled.