+1... I appreciate the inclusion of a low pass type control if that is what it is...again, confusion. Why don't they just call it that? This nonsense about it taking the place of the rear control on the cab though, is jut that, nonsense.
Unless that thing is 'pinging' the cab to get the x-over point of the tweeter for each cab it is paired with (which of course it does not do) then it cannot and does not even resemble the true functionality of a properly implemented L-Pad, anymore than a Low-pass resembles a shelving type, as you point out. An L-pad reduces the tweeter output only, of the cab it's designed with. A Low pass filter drops anything above it's selected freq which could be anywhere ...
In fact, one could reasonably employ both the Low Pass AND the L-Pad, depending on the coincidental freq alignments between the two (unlike the absurd claim that "the control takes the L-Pad and moves it to the front on the amp".
I think the TC stuff is amazing and ground breaking, but it's a shame that they cloud it with, IMO, spin that misrepresents functionality for the sake of marketing.
Now, if they designed it with a variable Q point along with variable attenuation (completely independent of one another)...wow...then you could have (if set properly) the ultimate L-Pad without the potential drawbacks (impeadance shift and such) that some caution about.