I agree that unless you have the information in your contract, I don't think all or even most of it is true. Hopefully someone who owns can confirm some of the conversion and points issues that I found in my 30-45 min research on Shell Points. Shell hides everything online and if you don't have access you can't see a lot of the charts. The info I found was from 2006-2009 from SVC and here on TUG. While my info is a little old in general points allotted to TS's don't increase ever but newer resorts might cost more to trade into. Another thing is converting points to hotel, air, cruise and other "partners" almost never decrease if anything the value you get when trading in the same amount usually decreases. With that in mind this is a link to a
Shell_Vacation_Club_2009_Points_Chart.pdf that lists all the points required to trade into each resort.
Carriage Hills platinum 2 bedroom gets 5350 SVC points so unless you own in a new section of the resort not listed on this chart, part of your fee is paying for 1100 additional Shell points. Now if your deed is being converted into one of the trust it may be possible that 6450 points have the same maintenance fees as your week but I kind of doubt it. In addition there is a Shell club fee that is paid. Even if your week is not going into a trust you would have to pay your club fees plus your regular MF's plus possible additional MF's on the 1100 points. If it is not in your contract you should call up and find out what your total MF's including any club fees would be on 6450 points. You should also confirm which of the trust club's you would be in.
Next for the conversion to airfare. Generally for all systems it is never a good deal. If members are finding a way to get more out of it then they are paying in the developer finds a way to de-value your points. The only chart I could find was this one from Shell News 2006
www.shellvacationsclub.com/shownews.html?id=212
At that time travel within the US could be had for 2500 points but from Canada to the 50 US was 3750 points. Travel within Canada was 3600 points. In small print it also indicates:
Point values for airline tickets are based on the average airfare of major airlines from each of the identified locations. If for any particular reason the rates exceed the benefit cap, the member would be offered the option to choose a different carrier or pay the difference.
So basically if the flight you want is up to a certain amount it will cost you so many points regardless of the true cost. If it is over the allowance they allow you would need to select a different flight or pay $ for the difference. Based on the conversion they use for the play deck on the previous page my bet would be 2500 would get you airfare up to $350 within the 48 US states and the 3750 for the Canada to US would get you tickets up to $500 USD. This based on 2006 rates. If you are lucky that would still be the value today. Most systems also charge a convenience fee to convert to partner points. I don't see it anywhere here but I would double check because many systems add an additional $25-$50 per ticket.
Finally as to renting the points. I found a document from SVC on this from 2006 or 2007 too but I can't locate it now. It indicated that rented points could only be used for reservations made within 60 days of travel. Although it wasn't explicitly stated I would understand that to mean you could rent points to stay in SVC properties reserved 60 days or less from check in- not use rented points to convert to airfare. But even if you could if my other assumptions based on the 2006 chart are correct you would be paying an additional $450 for $350 maximum airfare ticket or $675 for $500 worth of airfare tickets for the Canada to US flights.
Shell is smart to hide these until after you are past your rescission period when you get access to the web site. If you don't or can't the answers in writing you should definitively rescind.
As to walking away you would probably take some kind of hit to your credit but you would have to decide if the hit would be worth the MF's you would be paying for the years while it was affecting you.