Hi James,
Your in for a treat with NetHunter
The only suggestion that I could make in that regard is to go for a Nexus, but consider getting a refurbished one. You can pick them up for next to nothing, and you'll be more willing to experiment with some of the hardware hacks thats making its way to the surface. I'm sure you can tell that I enjoy the hardware side of things, and the only really realistic way to continue pushing the bounds is to do so while being financially responsible.
Coming back to your OP, I am seeing more and more manufacturers lock down on what hardware components you can use. As I mentioned Lenovo is at the forefront of this movement, and Asus followed suite shortly after. I hardly work with HP just because the manufacturers support is terrible where I'm from, but the more I think about it the more it makes sense that you would be encountering the same issues.
Best of luck with your experimentation!
Tulpa
