When purchasing, the costs work like this.

You paid $2000 per person for an H. The retail price is $3000 per person for an H.

You want an aft cabin which retails for $5000 per person. The difference is $2000 per person times two and you pay 50% of this rate (or $2000 more instead of $4000). So, if you want to upgrade to a particular suite and don't want to pay retail, but take your chances, this is the way to go.

We have done this. Sometimes you get a great deal and sometimes nothing you want is available. IF the cruise is not full and a lot of higher priced cabins are available, some hotel managers will deal even lower.