You run into problems if you start shooting things at different resolutions, for starters, you wouldn't be able to mix that content (just jeans/skirts/made it). I suppose you could convert the video to lower resolution but this just highers cost again. Cutting the video and producing two different versions doesn't do very much these days I expect, the one with the chit chat zero desperation will probably sell better and the cost of time 'wasted' not doing a bondage shoot is still there :S, this is the biggest difference to how it used to be
I don't think it's worth the extra cost for an hour - two hours of no desperation whatsoever. If your able to do other shoots in the meantime go for it, and do a holding as long as she can - could even throw in a few mins behind the scenes or something similar to the 'all day shoots', just like preparation, mixing some content from BIB that is relevant to B2B etc.
I'd save the one movie 'sets' to special holding contests between models or similar and special movies like 'wettest link'. Personally I wouldn't want to downgrade from HD just to have an extra hours worth of chit chat with no desperation, that I'd most likely only watch once, not to mention the costs Dave incurs from not being able to do any other shoots :S.
Also, on the topic of star, has any model for their first shoot done a holding for hours type movie anyway? Above anything else seems a bit extreme for a first shoot if they are still a little unclear whether they want to continue or not, suppose TTG isn't much better actually, but at least after the first shoot they might know to hold it that little bit longer etc