Dude it’s been implemented, no need for any < rant >s
Hold PTN + [PATTERN 1] + (COPY) - the screen should say pattern copied - then hold PTN + [PATTERN 2] + (PASTE) until the little four box countdown finishes. Done, pattern copied while still playing through the first one. Note you will have to select the second pattern in order to switch to it, it won’t go automatically after pasting. I tried to explain that clearly but if your having trouble shoot me a message.
*Edit - I messed up a little, its corrected now though