Haven't owned a TRex 500, but I do have the Goblin 500. It is a very nimble beast, especially with HV servos in it. Highly sensitive to collective movements. It can get going very fast, but it is very controllable and can fly slow and smooth in the right hands. I would not recommend it to a beginner, both because of crash repair costs and because of how sensitive it is. This should be a second or third model in your fleet.
Even when I did my maiden flights with this Gob 500, Ikon FBL, BK high voltage servos... Beginner flight mode setting in the Ikon; it was still far more sensitive to stick movements than anything I flew before, except maybe a nCPX or mCPX. This includes the Blade 300X, 550X, and Align TRex 700E. The beginner mode is *soft* on the Ikon, and it was still feeling like there was a direct connection between the sticks and the heli. No filter, no delay, nothing in the way. Sort of like what I imagine a flybar heli feels like, but perhaps even more nimble due to the flybarless head and low rotor loading of the Goblin.
It is a great machine. Fit and finish is excellent. Quality is top notch. And it flies fantastically. But it is not what I would have wanted to start out on.
The Blade 550X was my first big heli and I think it was the best one for me. A good balance of size, weight, agility, cost, and repair/maintenance costs. It was also a kit that had to be put together which was important to me, unlike other Blade offerings at the time. Also had local hobby shop support for it if needed.
So I'd recommend the TRex 500 if it is your first "big" heli purchase. If you are past the beginner stage, can do at least simple aerobatics, and can "control" your risk of crashing by flying comfortable maneuvers... if you know how to bailout and recover from a botched attempted maneuver, then go ahead on the goblin 500. You will not be disappointed.