Maybe some of the component parts are made by Miller, or Miller may own Hypertherm, but before moving out here to Michigan, I lived right next door to the Hypertherm factory in New Hampshire. That's also why I bought a Hypertherm. That was a mistake in my opinion.
First of all, they used a flammable covering on the torch leads, (I didn't KNOW they were flammable), and after being subjected to the sparks from the cutting process, they burned thru and severed the leads. Hypertherm refused to stand behind their product, saying I should have been more careful, and I ended up buying a whole new lead assembly. Being 'new' to plasma cutting at the time, I thought I should have known better and just 'bit the bullet' and bought new leads for somewhere in the neighborhood of 400 bucks, but I thought it was strange they'd use something flammable as a protector for the leads. (Live and learn I guess, right?)
Anyway, after about 3 months of use, the main PC board blew out, and I mean BLEW out! I thought someone had fired off a shotgun in my shop! Well, keeping in line with their apparent corporate philosophy, they once again refused to stand behind their product. They told me it blew out because there was alot of dirt on the PC board and my shop was probably "too dusty"! Imagine that... a welding shop with dirt in it! They also informed me a new board would run me about $1500.00, including installation, (that was 1/2 the price of the machine!).
Thankfully, I had leased the machine and I stopped paying the lease immediately. After another 3 months of arguing, they finally took the machine and repaired it under the warranty agreement.
The machine DID work pretty well after that until it was about 3 years old and the PC board once again blew out. I just said 'the hell with this' and scrapped the machine. I currently have a Miller and am quite happy with it.
I looked at a Thermo Dynamics machine before buying the Miller and it worked very nicely, but a TD rep I talked to at the welding show in Detroit told me he didn't think it would work with the Miller Trailblazer I have because of voltage fluctuations the Trailblazer produced. I totally respected the honesty of that rep for telling me that instead of just blindly selling me his product. You don't see that kind of honesty much anymore!
Sorry for the long post, but I hope it somehow helps in your decision of what machine to purchase.