I seem to be getting the hang of the high elbow approach which @CoachMorg recommended a mere 9 days ago. Once again I set a PB, 4:45min for 200m without the pullbuoy, suggesting that my 5:00 minute 'barrier' is well and truly overcome now.
I'm still working on technique and noted a fade in style and pace over the 6 lengths so then spent another 4 sets doing single lengths with the paddles followed by pairs of lengths without. As usual the current in the pool affected my pace but I was pleased to manage a length at 2:05min/100m (with the flow) as this approaches my previous pace with the pullbuoy. The load on my arms with paddles is moderate and currently one length at a time really does feel to be enough. Naturally even with a slower arm cadence my pace was faster, but not in a sustainable way. At this time I can't image doing a swimrun event with paddles over a 1000m swim.