We have a couple of lock-off units that are a great deal. Our situation is that each one is a 2BR unit, which can be split off into a 1BR + a studio (which also has a full kitchen).
* Sometimes we use them separately for 2 weeks vacation
* Sometimes we deposit one for exchange and use the other
* Sometimes we bring family members along to vacation in one of the parts while we use the other -- everybody has their own facilities, so it's a nice way to vacation together without too much togetherness!
* When we deposit one of the lockoffs into RCI, we split it apart and deposit both pieces separately. This gives us a lot more combined trading power than depositing the 2BR by itself.
The extra flexibility is wonderful!