I listened to the podcast last night and thoroughly enjoyed it. A wide ranging discussion and much to think about. Really interesting to hear the technical analysis of Birtwistle's approach to composition, and where he might be positioned in the contemporary music scene.
I smiled at the mention of Stockhausen, laboriously assembling his early electronic pieces. I have (another) dusty cassette of a presentation that he gave at the Barbican, London in 1985 where he describes the process: cutting and gluing bits of tape! Things have moved on a bit, as you point out! I quite like those early electronic pieces, they're successful in their own way, and I warmed to Stockhausen hearing him talk about it.