I think it's important to remember that timeshare salespersons are going to put their product in the best possible light. With regard to the future resale prices -- or even Disney's support of ROFR -- DVC guides probably fall into two categories: 1) those who have no clue, but make wild statements anyway to make a sale, and 2) those who have no clue and admit they don't know, or just keep quiet. I would not pay any attention to anything a DVC guide said about resale.
Even more importantly, what has happened in the past (however you do the math) is certainly no predictor of what will happen in the future.
Traditionally, DVC resale prices have been artificially propped up by ROFR in order to ensure that the resale market did not affect DVC's ability to sell "new" memberships too much. Bookwormde probably follows those trends much closer than any of us, and I'm sure can give you a good history.
However...there are several factors which have changed over the last few years and the future may look different from the past.
One factor is obviously the recession and its effect on WDW generally and DVC in particular. Obviously, revenues and margins have declined because Disney has had to resort to significant discounting to get people into the parks. DVC has also had difficulty holding their price levels for "new" memberships, and especially in holding their prices for points they own at "sold out" resorts.
In addition, the recession has caused many families to either sell their memberships or simply let them go into foreclosure. That has glutted the resale marketplace with inventory and put great pressure on Disney's ROFR policy.
The recession is not going away any time soon, and in fact, many prominent economists believe it will get somewhat worse before it begins to get better -- mayge a LOT worse.
Another major factor is in recent years (especially since the opening of sales for SSR) DVC has relied heavily on financed sales of DVC memberships. Some estimates say 75+% of all "new" DVC sales were financed. Disney's finance arm has taken a beating with those financed sales, and has been forced to take many accounts back through foreclosure. Foreclosed memberships either go back to DVC or they go into the resale marketplace. Either way, they make the market glut worse and put downward pressure on resale prices.
DVC has also been forced to raise the financing rates to very high levels, which makes payments higher and purchasing via financing much more difficult.
Between ROFR and foreclosure, DVC probably owns far more points than they ever wanted to own and the economic situation makes that inventory difficult to sell and difficult to rent through CRO.
As a result of all that (and other factors), DVC has lowered its ROFR levels, and we have seen resale prices drop substantially over the last couple of years. BCV contracts that sold 3-4 years ago in the mid-90s are now in the high-70s to low 80s. BWV contracts have dropped from high 80s to low 70s. It may be that the resale prices were overvalued and they are just falling to where they should be, as LouisianaDisneyFan's analysis suggests. Or not.
In the last couple of years, though, DVC has experienced something for the first time -- substantially reduced levels of ROFR support than they have maintained previously. Before we apply the history of the past to the future, we need to guess what DVC may have learned from the last couple of years.
Has the drop in resale prices in the last few years really hurt DVC's new sales? I'm not sure it has -- in fact, I suspect it hasn't mattered much. If it has not adversely affected their sales, I'd expect them to continue to experiment with weak ROFR support and see at what level there is an actual effect on new sales. Lower the ROFR floor and the resale prices will continue to move lower.
To offer an answer to OP's underlying question, I think resale prices are currently much more attractive than buying direct and the variety of inventory is very good. I'm not sure this is a great time to buy DVC at all, but if you're buying, I would certainly look long and hard at resale.