For me, better means that it does the same job while being cheaper in cost
set-up difference
the downside to the Caldwell is the set-up time...you need to align the chrono with the rifle and target. If your target is moved left/right, you will have to re-align the chronograph to stay inline
The FX attaches to the muzzle of the rifle, so minimal set-up is required. If target is moved left/right ..no additional set-up is needed
both chrono's usually stay in front of the rifle --The Caldwell can be moved downrange if you want to see what the fps is at a certain distance, but you had better put some kind of barrier in front of the base so you don't accidently shoot it--cause you will.
do both do the same thing? -- yes, they both measure fps
can you move them down range .. FX=no Caldwell=Yes
Which is easier to set-up = FX
so imo you would pay more for convience with the FX which is about 2x the price