I totally agree with you that the Sinfonion is completely bananas expensive, there are no words for describing how %&^(#*^# expensive the Sinfonion is and just don't buy it, saves you lots of money and you can buy so many more modules from that money, right? So who needs a Sinfonion? ;-)
Of course I am joking but yes the Sinfonion is expensive but no, it's seriously worth it, what I am trying to say here (my above text), that yes with the money of Sinfonion, you can get so many other nice modules but not really what Sinfonion can offer you here. Don't expect wonders from it either but if you are ready for the next step into more complexity, yet harmonised and get the things kind of organised (well.. when is something really organised within Eurorack, never I guess? ;-) ) then the Sinfonion might be actually the right module for you.
But before I continue: Hey, did you saw that woman just walked away at the end of the movie and leaves a very interesting modular synth there in that crappy building? Run fast and see if you can get that synth for yourself, perhaps she hasn't returned yet! I mean... come on... who walks away from a system like that and leaves it unguarded? (assuming the camera man wouldn't be there of course). Well at least Hélène does ;-)
Anyway, back to the Sinfonion. Bit more details then, with the Sinfonion you have 3 channels that you can use for your "regular" voices, each channel has a slightly bit different extra functionality compared to each other but the main functionality is about the same. Then you have another chord channel, it only requires one input but gives you up to four outputs to play for example (that's how I like to use it) with a polyphone module like the Doepfer A-111-4 Quad VCO. Last but certainly not least is the arpeggio channel, I love to use that one, very flexible in it's use.
That might not sound very complicated but it exactly gives you so many possibilities and complicated ways of using it harmonised or even unharmonised if you like (detuned). You can have slew option on channel 1 and on the chord channel. In my demo "The Cry Of The Modular Synth" you are hearing there that "Cry" sound using partly the slew option in combination with channel one. I am only using channel one here for this track (so "barely" using the Sinfonion actually):
The other voice you hear in that track (more kind of LFO driven sound) that's not done by or via the Sinfonion.
If you want another example of the Sinfonion I used, take this track here:
I fully utilise the Sinfonion here with all it has: 3 channels, channel 1 in A/B mode as well, chords, and the arpeggio. In that track I didn't used any keyboard or whatsoever to put "notes" into this track, that was mostly done by the Sinfonion. You just give it some bizarre sound and Sinfonion spits the notes (and chords) out you prefer, brilliant!
These are only two examples, I am not sure if Hélène is actually using a Sinfonion but if she would then that would be some other examples, but you can do so many various things with a Sinfonion, it's almost endless.
One thing to keep in mind though, it's not a sequencer in the classical way, it actually isn't really a sequencer; ACL likes to call it a chord progession sequencer and that's exactly what it is, the "only" thing you can sequence with the Sinfonion itself are the chords, all the other channels can't be sequenced, at least not by the Sinfonion itself. But that's not the idea of the Sinfonion anyway. See it more as a kind of master control of your entire rack getting all your stuff channed into the Sinfonion and get it a bit nicer out of it :-) Harmonised, quantised, whatever you like to call it. For details please download the Sinfonion manual, it's in English and it's written with some nice kind of humour. The manual will give you a good idea of what is possible, but actually that's just the beginning of it, what you are going to make out of it at the end might be way beyond what has been described in the manual and the Sinfonion is the tool for you that allows to do just that.
So yes, it's expensive but I have never regretted it. If I have to sell a few of my modules, the Sinfonion will be one of the last ones!
Though having said that, please do keep in mind that the Sinfonion becomes the black hole of your entire modular synthesizer! It sucks up any of the modules you have, it's very module hungry, because you need to feed it with inputs, so it can processes the sounds you provide it and then spits it out again and then it might again cry for more modules to do funny bits with the output. So you must have tons of modules (that's a bit the con of the Sinfonion) and Sinfonion will "slurp them all up" :-) Hence the reason I call the Sinfonion the black hole of my modular synth!
Have fun and kind regards, Garfield Modular.