So much will depend on your power, as to whether you see a huge difference between the two.
I picked up a xXx to 'replace' a very flat Flat Top Firebird that I put into a pond. Not the same thing. The xXx is closer to a very domey Firebird, IMO. RHBH, full power and flat, I get about 200 + ft. straight out of the xXx before it fades...and then it fades hard, not quite as hard as a FT Firebird. It's slower out of an anhzer FH than I expected, but it does always fade. I threw it hard yesterday into a serious headwind, say 25 mph +, and it flew about 250-275 dead straight with no fade.
In my experience, it's very similar in flight to a "regular" domey champ Firebird. It feels 'bigger' in the hand, (deeper and wider rimmed?) which is better for my big hands. I love it, been calling it my "Swedish meatball."
I find it to be more versatile than the FT FB, covers more shots, I've been throwing a ton of FH with it, in addition to the standard "meathook" BH shots.
I'm going to have to try the Trident also. I haven't thrown it yet, but need to cover that slot still. But my guess is the more power you throw with, the more you'll see a difference between the two.