The "slim keys" were presumably a conscious design choice and a little exploration into an untapped market. The fact that a large number of youtube videos showing off modular gear or desktop synths will have an Arturia Keystep 37 shows there is certainly a place for slim keys.
They make sense where space is limited and there just isn't room for large 5-octave plus full-sized keyboards. Additionally, not everyone is a classically trained pianist who can only use full size keys and don't have any issue using them.
These aren't mini keys like on the original Microkorg. In fact, they are bigger than the keystep 37 keys and feel nicer than those on the minilogue series which have also sold rather well.
I personally think they feel really nice for what they are and certainly don't detract from the experience of using it. I'm even enjoying it more than the Prophet 5 desktop/keystep 37 combination I'd been using previously.
It's definitely worth turning one on, hearing it in the flesh and actually feeling how expressive the poly aftertouch is.
I didn't say anything about them, being mini keys in the above post. That was clear from the first moment on and I said in one of my first posts, that this isn't my thing. My statement in the above post today is only about the pure feel. Our opinions may differ here. For me, they feel really really cheap, even for mini keys. That simply put me off so much, that I didn't even want to hear it. If it has keys, that I won't play, I'm not gonna pay for them. I'm pretty sure the Fourm sounds fantastic... as all Sequential gear. In fact, there is no bad sounding Sequential synth... it's all about the taste.
I guess it's not about a pianist CAN only use full size keys, but he WANTS to use only full size keys. I further guess that a good trained player can adapt to almost anything. But why should he/her?
In fact, bigger keys give more control. And I'm not talking about hitting the right notes. Bigger keys give more control over velocity and pressure, because they have the longer lever travel. And I can imagine how expressive the poly aftertouch is... but imagine how good it would be if you could use it even more fine-grained with a proper keybed.
Half of the Sequential community was hoping for a synth with poly AT, especially in the premium segment. It's really disappointing that they put that feature in a low budget synth like this first. Let's hope there's something for the "players" out there in the making ;-)
Still hoping for a Rev3 with switchable global/poly LFOs, 3 Osc's (for live the DCOs are perfectly fine... they don't go out of tune when the temperature on stage changes) instead of a simple sub oscillator with a proper mixing section, better filter and dual effects per layer. Give this thing a nice poly AT keybed and it becomes a live players dream.