I would say that MT would produce a far superior milkshake than OR... Theory based on the cows breathing much cleaner air in big sky country. Only way to really know would be to start the trip in OR (say Bend perhaps) with a round of local milkshakes, then pilgrimage across ID (with a stop for a shake there as a control point (no not potato flavored either), then over the Magruder trail into MT for the final shakedown, and perhaps some pizza. likely approaching the $1,000 milkshake, but easily worth it, and would be happy to serve as an unbiased officiant..lol, also an excellent field test of the new routing feature as a bonus....