In my opinion the other cuts of Wagyu beef are equally more tasty than its domestic counterpart. So if you are comparing a USDA triple A piece of brisket with a Wagyu brisket the taste difference will be the same as the Wagyu sirloin compared to the USDA triple A sirloin. Whether it is worth the money or not is debatable, but if money is not an issue why not try sourcing the cheaper meats if such a description could be applied to a Wagyu beef cut.
I would consider the recipe you are planning to use these cheaper cuts for though; my point in this is if you are gettings shins for a stew are you really going to preserve the flavor of the meat enough to make it worth the price.
I could see smoking a nice Wagyu brisket though. If you decide to experiment I would love to hear your opinion.
I have had the sirloin, ribeye, and a brisket not smoked :/ and they have all been better comparatively to their domestic counterparts. I have not had all cuts of Wagyu beef, so my opinion is limited to what I have experienced.