Best sauteuse for Hollandaise/Bearnaise/Mousseline sauces ?

I'm looking for the best possible conical sauteuse for my Hollandaise/Bearnaise/Mousseline sauces.

I cook on gas.

I own the Windsor shaped Mauviel M250c 20cm and 24cm, but because I'm a bit of perfectionist, I want a more rounded conical shaped sauce pot specifically for my Hollandaise/Bearnaise/Mousseline sauces.

I want it in a 20cm version and a 24cm version in the region of 2-3 liter in volume, not too small yet not too large.

My preferences are now copper only. I consider the Falk Copper Signature line but I'm open for other copper suggestions of course ;-)

I already own the Mauviel M Cook 5-PLY conical range, just looking for a chance to test out something new.

Mauviel only makes the copper version of their conical sauteuse in their thinner M150 copper line unfortunately, and I have been adviced against buying that line, as it's more for show than for real cooking.

Thanks in advance,
Claus

FYI Edited, because I now focus on copper only and not the Demeyere 7-PLY Atlantis line.