I disagree with some of your logic, and here is why.
Rack Rate - You have to use rack rates, as that is all we have to compare to, at this time. You can only not use rack rates if you are eligible for a discounted or promo room. If you can't go during promo periods, then no discount for you. If you don't have CAA/AAA, then no discount for you, not military, etc. Sure, Disney has been releasing many promos and discounts over the past few years, but just like many on here remind new DVC purchases to not count on any DVC perks or discounts, I don't think you can count on Disney discounts/promos either. If you shouldn't use DVC perks or discounts into your reasoning to purchase DVC, then you can't use it as a determining factor not to purchase either. I've called to ask MS about DVC cash rooms, and you even have to qualify for those - they've told me that when I've called, there wasn't a cash price available (not sure if this is right?). Some years, Disney discounts are few and far between, yet many of us have gone to Disney anyway, even at full price. I've already mentioned on several posts over the past few weeks, that I compared the summer discount room only rate for July (when we always go) for a moderate, to our DVC vacation, and our DVC vacation wins out - that is for 3 more nights in a 1 bed, and not a moderate room, with better ticket options (I only calculated a base ticket, but we always get APs and so our DVC discount is great, plus, we use for 2 trips). So, even with a promo, our DVC vacation this year is cheaper!
DVC weeknights vs weekdays - I totally see your point about weekend stays, but over time, this would be balance out, when the weekday stays are added, right? Also, next year that is a moot point, as the weekend stays have been lowered - have you worked those figures yet? Do you still think that weekends will cost more over cash prices?
Other options - I totally agree about other off site options, but again, many of them are drastically reduced timeshares used as marketing purposes (Hilton and Marriott) to get you to buy, so they may not be available. I have never rented a private home, but I do know from seeing posts on here, that this is a very feasible option for many too - cheaper than staying on-site, but for us, that doesn't make sense as we want to be right at the action, especially with small kids. We also would never compare to Value resorts, as we don't care for them, plus this isn't an apples to apples comparison - if people normally stay Value, then it will be pretty hard to compare that to DVC, as they are two entirely different things.
Financing - This may add to the cost of DVC, but it may not. My hubby's a banker, so we got a ridiculously low staff interest rate of like 1-2%. This gave us time to get the money together (we didn't have the large sum to pay out right away, plus CDN exchange had to be factored in), and even with some interest added on and our CDN exchange rates, we are still going to save money with our DVC over paying cash for Disney rooms.
The bottom line for us, is that we used realistic figures for moderate resorts as that is what we were used to staying in, and would be staying in for future stays, (used rack rates, and then hubby factored in some kind of formula for promos/discounts, but again, these aren't guaranteed), and we are pretty confident, depending upon maintenance fees of course, that we are going to come out ahead of staying at moderate resorts, and this is for mostly 1 beds, with some studios thrown in, but possible larger rooms as time goes on. When we factor in Deluxes/DVC Villas, which we never could have afforded anyway, we will come out even more ahead. We would never compare to Value resorts, or, to off-site, as we don't care for either of these two options, so sure there are cheaper options available to us, but since we won't partake of them, they weren't counted into our initial research. I think this is important - people should only use figures for off-site or value, if that is what they were doing before, or, would do in the future. This is the only way to get a true comparison, and if those figures are less, and the person is comfortable with that way of vacationing and it fits their family's needs, then perhaps DVC might not be that great of a purchase for them, as it will cost them more money then they had ever planned on spending, KWIM?
It's a very interesting and informative discussion, that's for sure! Tiger
We got a heck of a finance rate (0.99%), and a heck of a per point rate ($67.50/point), so we felt like this was a sign for us to bite the bullet. We took so many poster's advice, though, and only bought 200 points. We are hoping to bank, borrow, beg and steal to get my family and my DH's family into a Grand Villa next year, and then be happy with our 200 points for a while after that. If, after experiencing the DVC ownership lifestyle for awhile, we see that 200 points is too little, we'll add on. Like a pp said, there's a strong chance that the price per point will be lower 5 years from now than it is at this time, so we feel comfortable adding on as needed, rather than buying it all up front. I waiver between anxiety and excitement about the purchase, but I'm sure that once I make that first DVC reservation and step foot on WDW property, all those anxieties will vanish, and I'll be sucked in to the magic of Disney. 
I hope it's everything you want it to be! I also had anxiety and excitement when we bought in, but I wouldn't trade my DVC membership for anything!
