Well, I consider lying to your customers to be shady. That is a bit of a stretch though, but they have not said anything about the RS, M, or X v2 to have the same exact mechanism as the X. They also did the same thing by advertising the Air M as a completely new puzzle even though it's just an XS. I have a few problems with their 3x3's after the XS just being rehashes with no changes aside from the core and magnets, but I do have a problem when they don't tell you that its the same cube. Their marketing makes it look like they are all brand new and different puzzles and that's at least a little shady. I would be fine if they actually came out and said "Hey, The M is just the X, if you have one, you don't need the other one." instead of basically lying to their customers.
I doubt that their cubes are almost perfect. In fact, their performance hasn't gotten any better since 2016 when the Air came out. In fact, I think that the SM was their peak. Every cube afterwards has the same locking issues the original Air series had but without the stability. The only reason why their cubes are useable is that you are able to use the yellow GES and they are too weak for a cube as flexible as the gan cubes. Have you ever tried a post SM cube with purple GES? Its basically like trying to cube with a block of jello. I would also love to see them make something "stupid" that may or may not be good because that at least shows that they care enough to make something different. Also by slight variation do you mean a core swap? Thats the only difference aside from magnets between modern gan cubes since they are all either X or XS cubes with a different core.
Here, ill give an example of a rehash that was done CORRECTLY. The WRm is what a rehash should look like. Many people had a problem with the ridges on the GTS3, so they made a model without them since people were actually asking for it. Not only did they do that, but they also made the Dual Adjustmen system finer and included another set of springs for more customizability. If you went up to someone and said: "Hey, do you like your iPhone? Cool, buy this other one that has a different charging cable and no differences at all but we market it like its an entirely new product!" do you really think they would want that product? I think that the money should come from new innovations, something that gan hasn't been good at since the 356 Air and something they haven't done at all since the X.
I'm fine with them collecting the 3 jackpots they got from the original 354, X, and XS, but collecting 6 extra jackpots from the R, RS, M, Air M, Explorer 354, and X v2 is an issue. And I'm not sure how much money you have to invest to mix and match cores and hardware, I could do that for free, I'll just get an XS and put the core from the M in and boom, new gan cube!
TLDR; most of your points have some truth to them, but you need to see behind the facade that GAN has put in front of their products to realize they haven't done anything new since the XS and don't deserve to be seen as the most innovative company anymore, I honestly think that ShengShou is doing a good job at innovating right now than Gan.