I just bought an HDX 450 after seeing one that my best flying buddy just bought. I was there for it's maiden flight and it was rock solid right from the first. We were both very impressed. He let me fly is around, nothing fancy, just hovering, a few simple circuits, and a lot of pirouetting. It was very controllable and predictable. So I got one.
I bought my kit without the motor or ESC. I already had those. The kit itself was well put together. The only negative is that they shorted me the hardware bag that had the servo to swashplate links so I'm stuck until the replacements arrive. It's a little annoying but no big deal otherwise. One thing I like about the HDX over the T-Rex is the single sided main frames. I've not built a T-Rex but it just seems to me that this is a much easier and less complicated way to go than the T-Rex's stacked frames. The upper and lower rotor mast bearing blocks are act as the servo mounts. It's very clean and simple and the run from the servos to the swashplate is about as straight as any micro heli I've seen. Not that the T-Rex is bad in that regard, I just like the implimentation on the HDX, it's very simple.
The main rotor, washout unit, and swashplate come fully assembled and mounted to the main rotor shaft. The tail rotor gear box with the tail rotor and pitch change mechanism are also full assembled. The quality seems pretty much identical to what I've seen on the T-Rex SE. Without being able to directly compare the two, side by side, I'd say they're the same unit but I not 100% sure of that. The kit doesn't come with any written directions but it does come with a DVD that takes you through the full build process. I like the DVD but would prefer some written directions as well. They go through the build steps somewhat quicker than I can so there's a lot of pausing and reversing of the video to make sure I got whatever I working on right. It works but gets a little tedious after a while. One thing that they do recommend on the DVD is that the builder NOT assume that everything on the rotor head and tail are properly locktited. I checked all the screws on mine and found a couple of them that weren't as tight as I'd prefer but that's all. Everything else was nice and snug. So, at this point, I'm waiting for my missing hardware and will be installing the motor, ESC, receiver and gyro in the mean time.
I'll let you know how it goes when I get it flying!
Fly Safe,
Steve R.