Well, my parents have a Mainship and I have a Nordic Tug. I bought my NT with the intent of resale. Buy it, play with it, improve it, sell it, and buy a Taiwanese trawler 10' longer without any additional funding.
I think part of the value of a NT is due to maintaining a high resale value. I it is a similar to the marketing scheme that John Deere used for many years. Sell high, and take them back in at a high trade-in value. Don't let anyone else in the market and "fix" the price of a used tractor. Sell the used equipment at a high value, and over time the value remains high.
Now, to be sure, this "inflated" value can only be maintained as long as there is an inherent quality value, and an active market. I think the active market has dropped off considerably.
I think Nordic Tugs are well built boats. I go on board other brand boats (not custom) and see where corners are cut. Generally speaking, people judge boats on the tactile and visual aspects. I go to boat shows and look in the bilges, corners and where bulkheads are connected.
Does this matter? In the whole scheme of things, probably not.
I recently spent money on having a custom kitchen made by a cabinet maker. Once he was done, I had him do my laundry room and ensuite. Had him make new doors out of old growth fir, too. Is it any better? Probably not. In fact, a lot can be said for industry design, efficiency, and value. I'd say a lot of mass produced cabinetry (and boats) have better features, than my custom stuff. So that may be why I like my Nordic Tug, and may never part with it. I prefer small, simple, and custom.
But really a Mainship would likely be more desirable on the ICW. When I visit my parents back east, we spend a lot of time on the flying bridge, but I wouldn't want it out here in the PNW.