Dean -
You make borrowing sound like credit card debt!
If you go to Disney every year, you want to have enough points to avoid borrowing. For us less than every year folks, the banking/borrowing combination is how we maximize our points.
I have 7 points banked into next 2003, will get 150 for 2003, and take a trip in 2003 that costs 227. So I'll borrow 70 2004 points from 2004. Then I bank 120 2004 points into 2005, get 150 points in 2005 take a trip that uses 314 points in 2005, borrow 44 points from 2006, bank the remaining 106 points into 2007......rinse, repeat,
(all years are use years.....the math may be wrong).
When buying resale, look for a contract that doesn't have a lot of points borrowed - unless you are getting a bargain and the cost is a big factor.