I don’t layer the AK with other synths because I use its onboard SEQ.
I use the OT to clock AK and AR, and to control external samplers and synthesizes.
The AK sometimes controls a modular but that is the extent of its layering with other synths.
Sometimes I use audio voices in the OT to play back textures or to make quick melodies using samples.
I usually layer other synths together via one of the OTs MIDI tracks.