The new higher wattage LED modules work OK for under cabinet lighting but not the older fraction of a watt modules.

The Trac 12 system does not meet Title 24 if you are designing for California because it is modular and you can easily replace the LED modules with something else. Talk to your inspector to avoid a surprise.

not CA... electrician seems very familiar with code so i imagine it will pass.
my question really is whether the fact that you can move them is actually useful for under cabinet or just marketing / something to make them stand out from all the other options...

Trac 12 can accomodate different lamp choices. I think this is just one more option for the product line.