That's the old-school Jazz Trio. It is a great blend of instrumentation.
The drums weren't great, anyhow. Roland SPD-20 "brain," a Roland FD-7 hi hat pedal and one PD-8 that I usually had set up as a snare. As a kit, it needed a lot of work yet. The hi hat controller had a lousy feel, there was no kick pedal, and no-where near enough pads, even including the surface of the SPD-20 itself. But even if it was complete, that's simply not the direction I'm going now.
See, that particular arrangement of controllers is to simulate this:
The pic above is a render of a kit I created in 3d. (Complete with multiple options, textures, fully adjustable and animatable...but that's not the point). The point is that an element of the sound is placed to be triggered from each limb. The right foot tapping the kick on the 1 and 3, left hand on the snare at the 2 and 4, heel-toe on the hi hat pedal on the quarter notes, and right hand laying down eighths on hat or ride (on the kit above, that's a hybrid crash-ride).
And many, many variations thereon. It's all about the coordination, and the idioms descend from the physicality, from what is easier to reach in conjunction with what or which movements naturally coordinate. And the best way to get it is to have those controls with that response in the right positions. You pretty much need something, whether it is an actual acoustic drum kit, or a set of sensors, sprawling out and taking up space in that arrangement or close to it.
Which is partially what my friend was looking for. But also, honestly, even if you are simulating timpani or tin-pan, bongos or part of a gamelan, having big pads to swing a stick at is better than trying to do it on piano-style keys. Or even those cute little baby touch pads on some keyboard controllers.
And the natural sounds are not there. All the ways the tones interact, all the side noises (wanted, unwanted, or merely accepted), are part of the character of the instrument and the intimacy and presence of the sound.
It might seem like the electric bass and violin, and the Behringer 61-key, are counter to that idea. Don't be deceived by the terminology. Both my first violin and my new bass are electrically amplified, but the sound of the sound is entirely physical. It is the same vibration of strings as a true violin or an upright bass.
Well, sort of. The tone on both (the U-bass is a solid-body model) is simpler, lacking the full body resonances of a primarily acoustic instrument. But they do share -- in fact, because of this same lack of natural acoustic amplification, they even have more -- of the finger noise and bow noise and fret buzzing and all of that.
In short, both have a tone that is far too expressive. Every move my fingers make, intentional or not, is broadcast by the instrument.
You might think the keyboard is the odd one out here, but not exactly. The majority of keyboard instruments share one dirty secret; they are mechanical. If I fret on the bass where I place my finger and how I place my finger matters in the resulting sound. If I play a note on the piano...it plays. So a MIDI keyboard sacrifices very little of the nuance of the performer.
(I hasten to add -- that's when it is used to mimic keyboard instruments. It captures fairly faithfully a piano or organ performance. It fails to deliver the necessary control and thus nuance of a string or wind performance when it tries to mimic one.)
So I've been seeing a lot of stuff done with novel orchestration, and with hand-made and improvised instruments. I am still intrigued by the idioms of specific folk musics, of how a bluegrass fiddle is different from a klezmer violin, of the kinds of flourishes typical of an Irish penny whistle, but I'm becoming a lot more cosmopolitan in my arranging.
I'm just as happy, now, putting together groups of instruments that sound good, with whatever interesting techniques each player can muster, as I am with trying to "play the game" and stick with the style, idioms, and expectations of a classic jazz trio.
And in any case...I won't have the piano I want until I've gotten around to hooking up that Raspberry Pi-based keyboard module.