It's kind of hard to believe that Haas & Fadal were across the street from each other ten years ago, huh?
Does Fadal even make the TRM anymore? I would imagine that you're upgrading to something bigger but I went to their website just about a week ago looking for the TRM. It was nowhere to be found.
And it's ironic because that was exactly the machine I was going to look at (Fadal TRM) as I was cutting through the Haas booth at 2002 Westec. Back then, the TRM was a wild dream. Gene Saltis of Haas intercepted me and the rest is history. Today, I own two Haas machines.
Based on what you already know about the Fadal, I'd at least give one a serious look. They must do something to remain competitive in the market (cost, performance, rigidity...something).
As for the transition to the Haas control, I don't know: I've only owned Haas and this was my first real CNC machine experience. With what I know about transitioning to different CAD programs, once you've learned the basics, the skills move pretty easily.
The same has to be true of the controls. Once you know your way around G-code, setting tool and work offsets and changing machine parameters, it's only a matter of finding where they are in the new control. I've found the Haas to be very easy to use.
And if you're doing your programming offline, you won't even care about the editor anyway. It'll be about storing and running the programs.