i have them both and i can safely say there’s almost no overlap.
(as you probably know because you have it, but highlighting for other readers) the granular engine on S-4 is way more complex, it’s realtime, and pitch modulation + quantization + 4 modulators with an insane amount of shaping possibilities (yes, shaping the modulator wave itself) makes it lightyears ahead compared what TV offers. (and I’m just talking about the Mosaic device, not evne taking Rings into account)
on the other hand, the POLY machine of S-4 is quite basic with a mediocre filter (an obviously you need an external sequencer to be able to sequence it)
granulation-wise, there’s fundamental differences between realtime granular fx (which is based on a constantly refilled buffer, which S-4 has) and buffered granular fx (where buffer is prefilled, like TV) and they produce very different results.
i’ll be brutally honest, i’m slightly disappointed with the grainer machine. and i didn’t even have high expectations (it wouldn’t be a GR-MEGA ofc), but i expected at least to be able to control the pitch of grains (even if it was a simple 1 octave up/down shift) but it’s not there (hopefully they add it)
that being said, TV is a keeper because of all the other things it can do, not what grainer can (or rather can’t) do.
so for anyone that got hyped by the grainer machine ALONE in an oddly specific scenario where you consider selling S-4 to get a TV with the money, i’d vote against it. using both would be a very very nice combo though. (and this is coming from someone who almost always keeps a project “constrained to a single box” despite owning lots of gear, mainly because of laziness and lack of proper studio space, and also creativity thriving in constraints etc etc but even i will hook them up together and use S-4 as a send fx + field recording player that can mangle sound to the hell and back)
besides granulation, S-4 has one of the nicest saturators i’ve seen/heard in any gear i own (and i bought and sold all generations of analog heat ahah). even the dirtshaper in TV feels very boxy and lacking definition despite the rectification algo it has.
so all in all, S-4 feels more like it belongs to a realm of modular (crazy modulation possibilities, to the extent of “sequencing” through modulation), or maybe even a norns-like world, where it’s very good at doing something probably only it can do, and it’s more like a “tool” in your toolbelt. (master of one)
and TV is a global citizen, a proper groovebox that can do almost everything (jack of all trades, master of none. well maybe except sequencing, elektron sequencer is the king of sequencers
) so it’s very welcome to have “some” granular action there, but it shouldn’t be a deciding factor on that particular subject alone.
if it matters, i travel quite frequently and i can only get only 1-2 pieces of “relatively portable” music gear with me. since i acquired it, S-4 permanently occupies one of those slots. but i can safely say TV will probably be the second device i’ll bring along most of the time (instead of a rotation between M8, Deluge, DTII, DNII, Push3SA etc)
i know this sounded like i praise S-4 a lot, but believe me i’m being objective. there’s a lot of things i hate in S-4 and lots of decisions from devs that i don’t agree with, but still even at its current state, it fills a very particular gap i have in my (g)ear, and it’s currently irreplaceable for me, at least for now.