Has anyone researched how much longer does it take to get from an off site hotel to the ticket gate, compared to using WDW transit when staying on-site? I read a blog recently where a person with an AP was evaluating the new security at MK and I think his time from car getting into WDW property (driving under the Welcome signs) to the ticket gate at MK was something like two hours. That did not include the time to get from a specific location outside of WDW to the Welcome signs (the blogger was a local).
To me, time has a value. I don't know exactly how much of a price difference would convince me to pay more on-site, but it definitely would be something to consider.
Of course, if you are using your car inside WDW, then the comparison is probably not of any value.