I reckon on this one we'll have to agree to disagree.
All of the reports that I have read of people doing trips from Panama and the US westwards across the Pacific (and I've read pretty much everything that I could find) indicate that the voyages they did in total distance, supported by the time it took them to cover the distances of the assorted legs didn't vary much from the rhumb line distances. I've even gone to the trouble of visiting a chandler in NZ who deals in used charts that he buys from passing cruising boats. Their courses are still on many of the charts and they're about as staight a line across the ocean as you can get. And not just one lucky fellow, all of them.
Remember this is the Coconut Milk Run. This is a world of following currents that are actually invariable and trade winds that pretty much stay the way you expect them to (mostly on the beam). Yes there will be weather cells that will have you changing course for a day or two but this is not a voyage where you're beating all or even most of the way. This is a downhill run in the truest sense of the sailing world.
And the routing charts I have examined that are created from many decades of accumulated data support this contention. Whilst I don't expect to use a ruler to plot my course from one end to the other, 60% more than the rhumb line distance is just plain wrong.