I've been looking at the same thing. I've been researching this forum and this is what I've concluded:
You better find an owner who actually owns at GCV and have them book it before the 7 month window opens up.
The cost per point from GCV owners is higher ($12-$13/point verus $9-11 at other properties), but if you can get it, it's still cheaper than a regular reservation at GC.
You can use the points for other properties (and for GC regular hotel rooms), but with the high point cost it might actually cost more than a regular reservation. For example you could stay in the Disneyland Hotel (I don't know the point cost for a non Villa hotel room at the Grand because they just started opening these up this year) for 4 nights in July in a standard room with four people for $1600 +tax (the GC for this same time period would be $2000 +tax). If you book a standard room through DVR it would cost you 44 points a night for a Sun-Thurs stay (that's what I searched to get the $1600), which would total 176 points (44X4) at $12 a point that comes to $2112. So even with tax added on, unless you can get the points for LESS than $10 a point, you're better off looking for another deal.