For "off season" travel, I usually use the Interval Getaways. They are usually pretty dirt cheap, and you only pay when you need them. As opposed to an annual maintenance fee on points. I think they actually sell short stays also, but we always end up purchasing full weeks even if we only use a few days (which is pretty rare).
I looked at II Getaways for Hilton Head to test the theory on Points vs Getaways, the only dates I could see available for Marriotts in the II Getaway system were early December through the end of February. I looked at the off-beach Harbour Point/Sunset Pointe properties and Barony, Grande Ocean, SurfWatch, and Monarch. Here is what it would take in DC Points for a week and the MF cost based on the proposed 2016 MF cost for Trust points of $0.5025 compared to the Getaway costs (an enrolled owner with a lower MF/point cost would look even better):
Harbour Point/Sunset Pointe
- 400-675 points @ $201 - $339; Getaways @ $547-$1147
Barony Beach Club/Grande Ocean/Monarch/SurfWatch
- 550-2450 points @ $276 - $1231; Getaways @ $597-$1197
The highest DC point requirement Barony/Grande Ocean/Monarch/Surfwatch weeks (2050-2450 points) are for OS/OF in February; not sure if you would get OF with a Getaway, but maybe you would in off-season. The January points costs for Barony/GO/Monarch/SurfWatch would all be less than $600, even for OF. The highest priced Getaways are Christmas week. There is no DC point premium charged in Hilton Head for Christmas week.
So generally, off-season DC points MF costs in HHI are less than II Getaways - in some cases, less than half the cost of the Getaway.
In theory, our meager 3375 DC Points could get us 8 weeks at Harbour Point/Sunset Pointe in what is essentially Bronze Season, or 5 weeks in the Points equivalent of Silver Season. With Getaways, that would cost at least $4400 for the 8 weeks in Bronze or at least $3300 for the 5 weeks in Silver.
This doesn't address availability of Points reservations vs Getaways, and it may not be true for all time periods in all locations, but I think this confirms BocaBoy's general theory.