I have this working with many more than just 3 devices. I do like the tactility of actual sliders to the iphobe or ipad with mididesigner pro (which is a fantastic app)
I have interconnected the following devices all via bluetooth. I use yamaha bt midi din (aka widi) adaptors and when talking ipad to iphone i use midittr.
Yamaha ck61 - portable good sounds no percussion
Hammond sk1 - Tonewheel
Yamaha reface yc - surprising handy organ
Yamaha reface dx - synth
Yamaha reface cp - lovely EP
Yamaha cp4 - weighted key heavy but sturdy oiano
Roland sound source (percussion) - happened to have it
Korg studio nano bluetooth - very nice 8 slider, 8 rotary and a zillion buttons (but missing that 9th drawbar for organ work)
Boss fs1 bluetooth - 3 button footpedal
Boss exp bluetooth - wireless expression pedal
Boss rc600 looper - beast of a looper, hard to tame but sound quality is top notch
Ipad 128b newish ipad mini - 128gb ram
Ioad 128a older ipad (fourscore) mini - 128gb ram
Zoom l12 mixer - really love this and it records in 12 tracks too and has 5 monitor outs
Pair of Bose Sp1 pro (battery powered) PA speakers (portable and off grid)
Pair of JBL EON front of house speakers (heavy and loud)
leslie 2101 mk2 - heavy
Leslie 2103 bass unit - heavy
Ryobi 18v 6ah battery and 150w inverter
Ipad 128b has midifire as the spaghetti controller (using streambyter applets extensively). This is the heart of it.
Ipad 128b also has midittr receiving from ipad 128a
Ipad 128b has mididesigner pro essentially reporting on whats happening in midifire
Ipad 128a has sunriser, korg module, funky drummer and sometimes b-3x running in background mode. Timing source is the rc600.
The idea of useage depends on the circumstance. It started with wanting to grab two tiny reface keyboards and an ipad and being able to make sounds off grid reliably and over 5-6 octave (piano, organ, ep, bass, brass).
At home (studio) i use the hammond sk1/73 and the Cp4 and i love looping too (friend in a box). But its a “rig” and not that portable.
I was half way through the reface centric build when I came accross the yamaha ck61 and this is the device i grab if im going to a friends for a jam. Its great!
Obviously theres an element of too much time and some extra cash about it but it has kept my mind occupied and i have a lot ive learnt. Ipad apps and bluetooth midi are simply awesome! I know my limitations as a keyboardist and like the golf hacker one goes one the journey of trying to make uo for being average by buying more gear.
One thing I do love about my stuff is I can use any combination of devices and if i retune one they all follow suite. (Im not very adept at playing in B major for example). The flexibility and with two Bose so1 pro speakers the dream of being able to go bush and play off grid is very appealing.
If anyone has any questions about this stuff Im happy to assist. I have recently helped a guy to drive the hammond b-3x app from a digital accordian. I think hes happy.