Hi George!
Excellent question! First, I should just say that there’s basically no risk of damaging the Beginner’s Shamisen due to playing too fast/hard. In tsugaru lore, there’s kind of the story about the shamisen becoming thicker because the thinner models broke during fast/hard playing, but I think that’s a bit of a myth. True, the skin would’ve ruptured more often, as skins were more delicate back then, but the thick neck “Tsugaru Shamisen” wasn’t coined/marketed until the 1950s~1970s, so there’s a solid 150 years of tsugaru style being played on nagauta, jiuta, and minyo shamisen.
Another point about the minyo shamisen and Beginner’s Shamisen. Both are made from the same type of wood, and are very high quality for the price. The one benefit of a minyo shamisen would be the slightly wider sao (chuzao vs hosozao), which does make playing a bit easier.
The pricing is a rather interesting matter. In Japan, there’s automatically a price hike for anything tsugaru related, because it’s the most popular. Many years ago, I contacted a shamisen maker about making affordable shamisen (this was before the Beginner’s Shamisen). Basically, even though making a nagauta shamisen and tsugaru shamisen are basically the same process, there was an instant $500 price increase, just for the simplest model. In any case, the reason for the minyo shamisen being cheaper is not due to being lower quality, but is due to the markup from anything related to the popular tsugaru style. 
A bit more explanation on the pricing of the “Karin Minyo Tsugaru Shamisen". Basically, the Tsugaru Shamisen TSY-1 (and such) are priced the way they are because they come from a regular shamisen supplier, who adds on his profit margin. My partner also adds a profit margin for himself, and I add on a bit for myself as well (because I have to make a living ), and so the price increases with so many middlemen involved (as well as from the initial craftsman charging more for making a tsugaru shamisen). For tsugaru shamisen, I heartily recommend the Raven for getting the most bang for the buck. I have a direct connection to Tokyo Wagakki, and by adding only 30% profit margin, you can get truly masterpiece level craftsmanship at really the lowest price possible (most shamisen retailers in Japan add 200%~300%).
Let me know if you have any other questions! I’m going out of town tomorrow until Sunday, but I’ll try to write when I can.
