Owning at either VB or HH, with the sole intent of staying at WDW, can be a risky move.
First, while the upfront contract cost is cheaper, as already mentioned, the MF's are around $2.00 more than some the WDW resorts. It doesn't take long for you to eat away at whatever savings you get.
The other piece is that you are then limited to NEVER being able to book at WDW until 7 months prior to vacation. While there are very few times in the year where you will find NO availability at
DVC resorts, there are times, even at the 7 month mark, that things are limited (ie: early December).
Without being able to secure something during the home resort booking period, you may be forced with having to move resorts and not being able to book the room size you want.
At least if you choose a resort at WDW, you can book something at 11 months and then trade out at 7. Unless you will absolutely never book prior to 7 months, you could be setting yourself up for disappointment.
And, the POS (if I have read it correctly--someone will correct me if I am wrong) only guarantees you the right to book at your home resort. At any time, the right to stay at other DVC resorts could be changed--not likely, but possible.
Now, if you see yourself using VB on occasion, then it might be something to consider.
Good luck!