Taking a deep look at the user manual pdf that TE provide on their site..
The
#16 keyboard doesn't look like it can be powered externally, batteries only. And each time you want to change them you'll need to take the whole thing apart, unscrewing and rescrewing the top and bottom. The 4 AAs will probably last a while, but still, no easy access a la pocket operator.
In the
#170 we got the same problem, only this time around the batteries to change aren't 4 but 12, still 4 below the keyboard bit but 8 more that power the rest of the synth. And again, you'll need to take the whole thing apart to change them (I guess this will be even more cumbersome if the batteries drain at different rates, between keyboard and synthesizer).
The
#400 seems to be powered by just 8 batteries, only this time you can access them without taking the whole thing apart! In fact, the 400 is the only one out of the three with a fully sealed enclosure for the modules.
Let's talk about the modules: they only get very brief, general explanations about what each of them can do. No technical details, no patch point overview, nothing. I hope TE give us more details about what the modules' capabilities, either updating this pdf or with proper instructions once you receive your unit. Otherwise.. I'm worried. I mean, right in this manual it says that each module has it's own box, but the box contents consist only of the module itself, 8 screws (4 attach from the outside and 4 from the inside) and 4 screw leads. Not good.
I'm forced to look at the patch examples to try and deduce what each input and output on these modules do

the words on the faceplate are a bit too vague..
Seems like the filter has got 2 cv inputs, and they both control the cutoff frequency at the same time. You could easily set up something like 2 LFOs or an LFO and an envelope modulating the filter at the same time.
All these VCOs have multiple outputs for their single waves, so you won't be needing external mults. In fact, most of these modules have 2 or 3 of the same output, which is handy.
Some patch points and knobs I still don't understand. Like the ones on the VCOs labelled as "control". Control of what? I'm guessing it's pitch CV, but then why have a separate input for pitch CV coming from a keyboard? Why label them differently? Am I missing something?
Also, good number of cv outputs but not as many cv inputs, that's for sure. Wanna play the 3 oscillators of the 400 in unison? Well, I hope you have an external mult or of those star-shaped splitters. Or you know, this 16 keyboard which has 3 identical pitch cv outs, would you look at that.
I like the concept of these TE modulars. I just don't understand some of the choices made.. I want to like these more, but I can't right now.
I'll wait for demos