I bought a CX-equipped Trek Powerfly in Jan. Have not tried the Active Line so cannot offer a comparison, but based on a few weeks of first impressions I would suggest the choice depends on your usage.
When leisure riding in the country I rarely use Turbo but my commute through central London is 95% Turbo. The extra torque is very useful when dicing with traffic.
I think Turbo on the CX is 300% at 75N and on the ActiveLine Plus it's 280% at 50N - but on the flat from a standing start on Turbo both go like **** off a shovel basically...
I also cycle almost entirely 'off road' (river and canal banks, old railway lines, forest tracks etc.) and the Activeline Plus is better for me as I only use the assist to moderate my HR under 150 (so keep it off a lot of the time).
Of course if 'off-road' means MTB trails then you'll want the CX.
IMHO It is simply about the gradients you need to regularly go up. Up to 15% (or possibly a bit below if you are very heavy/unfit) you are best with ActiveLine Plus IMHO. Over that it's CX.
The CX will work on the flat/with lesser inclines of course, but it's more expensive, heavier, noisier, uses 30% more battery for the same distance, has significant drag when off/over 25mph (unless derestricted) and is likely to be worse for wear and tear/reliability than the ActiveLine Plus.
So you only want it in preference to the ActiveLine Plus if you really need that extra oomph getting up steep hills (or want to derestrict and need more power for added speed).