Hi gearguy,
First I will admit that my actual culinary skills need to catch up with my cookware preferences.
I would rather go larger on a rondeau than smaller. I think 28cm is a good size for a rondeau. In fact if you are after a heavy gauge copper rondeau, instead of getting a single handle, 28cm 2.5mm saute, I think the two handled 2.5mm rondeau is more manageable weight wise.
In 24cm range of a pan that shape I would prefer the single handle saute, but if someone was maybe a little older or female, but still wanted the heavy gauge stuff, I think a 24 cm two handle rondeau would be a good match.
I tend to like the deeper rondeau and even a rounded bottom one. Not sure about a side by side, but I believe the 28 cm Matfer 2.5mm is more shallow than the 28cm Mauviel 250c/b. I have the 28cm 250b and like it a lot.
I think falk has some rounded bottom options and De Buyer Prima Matera is 2mm but one model has rounded bottom.
I prefer the lid also. Do you like brass/bronze, SS handles, or cast iron?
