A lower MIDI controller kbd can of course be split into 2 (or more) zones. When I had the T2, and the CME 76 I split the CME at C3.
The lower trigered the chord changes, the upper was assigned to R3. It worked.

what I want to hear is how this song would sound on a T3/T4 played in a similar way as Leigh plays this Wersi Duo..

Even just without the lower would help me to compare. But I would like the lower as it is what I will do if I get a T4.

This should be both easy and fun for someone here??
Anyone with a 2 tier stand (or equivlant) and a MIDI kbd can easlily do ths.

Lee S.