SHRINK-
care to clue us in as to why some "sharps" don't buy from 7 to 7.5 if they would buy the 6.5 to 7?
If someone thinks there is value in buying the 6.5 to 7, then there must be value in buying the 7 to 7.5. Frequency of a push is the same in either scenario, so you are either buying a loss to a push or a push to a win.
The only reason I would think that one is profitable and the other is not is if you have some data that says the frequency of a line of 6.5 landing on 7 is greater than a line of 7 landing on 7. Otherwise, both should have the same value.
Unless it is the psychological effects of a loss than are trying to be eliminated...