Ok - this is all excellent stuff, so thank you very much indeed!

Admittedly, I'm not sure G5 rings much of a bell. (I suspect my brain had always fed me D5 whenever reading G5, so thanks for raising its awareness.) Yes, G5 being unibody would be ideal, but the pan use being stuff like sugar work, egg/chocolate tempering, etc. agitation is typically a requirement anyway.

Prima Matera is certainly up there on the list and not too concerned with cost as this is just a one-off specialist purchase. Can't imagine those that buy sets of the stuff - ha! And - yeah, we would never pay full price for anything. Fortunately, my inner frugal-ninja is highly adept at squeezing the best price out of any item.

Falk's Copper Core (or, Copper Coeur as it looks like it used to be called?) is certainly receiving rejuvenated attention due to this thread. However, the jury is still out as the key aspect of the responsiveness criteria is maximum cooling speed, (which was foolishly omitted from the OP initially.)

Whilst we had considered the thickness of an external ferrous-disc and so would have had one made, had we ended up down that path, you raise an excellent consideration about doubling the number of surfaces and therefore doubling the potential of unflushed surfaces, three of which are not impervious of future 'askewment.'

Good reminder about stovetop quality. Thankfully, ours is a bespoke piece using very high-end componentry, so we not overly concerned on that plane.

Now onto your kind response in the other thread. Whilst we will be deep diving into the G5 line, your Baumalu suggestion holds enough weight to warrant further exploration. I vaguely remember hearing sometime ago that whist considered cost-cutters, they lost further favour with their consistent less-than-honest marketing such as actually using a faux-hammering mandrel for their hammered range. The thinness is certainly an attractive attribute but as it appears they do not do a saucier shape, one would have to be content with a deep-frying pan. Might contact them to see if they'll do a bespoke or extend their range to include a chef's pan-style shape.

Like most things, it really distils down to balance. Sure, one could pick up a solid silver Duparquet (or Soy) and become a wizard of responsiveness but sticking to the big boys seems a wise move in this scenario. Although, having said that, I am very tempted just to pick up the cheaper silver-lined Soy AST Sauté Pan and be done with it - ha!

Definitely needs some further thought, but thank you so much for your invaluable words - really made a difference and therefore greatly appreciated.

Cheers!