If you think of Hilton points as anything more than a stopping place for miles being "laundered" from A to B, you also have to keep in mind that a HHonors point is worth about a third of an airline mile. (This is no more a value judgment that comparing feet with meters is. They are different units of measure.) So, your lose about a third of their value on the inbound trip and about half of the remaining 2/3 on the outbound trip, or about the same amount in each step, even though the numbers without this exchange rate adjustment might suggest otherwise.