So, I was going to say a piano keyboard as one of my choices, too.
So here's the thing: yeah, it does help an advanced pianist. The problem with an isomorphic keyboard is the idea that you want to be constrained to a single scale.
Now: I love my Push, and I love its iso implementation; it leads to all sorts of things I'd never come to on a chromatic keyboard.
But similarly: all the "wrong" notes are actually where interest can lie: in tonal music, there are many possible ways to harmonize a melody, or to write a tune over chords: lots of things fit. Sometimes, happy accidents turn out not to be accidents at all, just a scale you hadn't thought of. I can shift from A flat major into B minor in an instant's thought on a piano - and only with some well timed button presses on many iso keyboards. (That's before you get to the fact that whilst A minor and C major and D dorian (say) have the same notes in them, they have very different intents, and sometimes you come to a series of notes as you play, rather than deciding them up front: iso keyboards start out by forcing you to choose a starting point, even if you then use them in very different ways).
Similarly: whilst it's lovely that same-chords have the same-shape... I do find inversions harder to think about on the iso layout, wheras they come instantly to me on a piano keyboard. Maybe that's just experience, tho.
It's also worth noting that different keys do feel different - at least, they do to me. I find D flat and A flat majors warm and lush, and G and C a bit dreary; temprament is a thing that has meaning; not all identical intervals are made equal, as it were. Too much jazz too early means my hands tend to gravitate to a B flat minor 9 - D flat major 7 - when I approach a piano keyboard. Lovely and rich. Iso keyboards have the effect of making me use less interesting harmony; usually, that's a good thing, I stick far too many 7/9/11s in otherwise - but a choice that's very hard to fight.
The advanced use is much like the advanced use of any tool or machine or instrument: having choice available and not using it. There are more options, but I have the control to limit myself to them - when I look at a keyboard during a solo, I see it isomorphically - obvious notes in the current chord, less obvious ones, transitions to the next one, obvious wrong ones. If you gave me an isomorphic keyboard, I'd also be able to solo on that - but it'd lose a few elements, some of which would be mistakes (knowing me) but others... others I'd perhaps rather have.
But: the choice of tool is a choice, and interesting things come form it. I've had a lot of fun wrapping my head around the Push iso layout, and use it a lot out of choice - with somewhat pianistic technique - and yet it's also nice to force myself to return to a real chromatic keyboard.