Hi,
I have no experience with those standard 2,6mm lighter alu ply pans you are considering, but I have cooked for years on a similar induction cooktop as you are on currently, and I have 21cm hobs on my current one also as mentioned.
You already have a Proline in 24cm, why are you considering a thinner pan now and of what size and shape?
What I can say, is that the de Buyer and Mauviel clad stainless frypans in 28cm are small bottomed, similar as your de Buyer 28cm carbon steel. If you find the evenness performance of your carbon pan is enough, then you should have no problems with the ply pans in similar size.
Typically if you ask online, you will get varying answers. It seems to me, that most like a bit thicker alu clad pans than the ones you mentioned though, eg Demeyere industry 3mm.
I have only Falk Coer for clad pans. They have 1,9mm copper in the core and are of 2,5mm total thickness, rest being stainless steel. In heat capacity, this is equivalent to an alu-clad pan that would be about 3,3mm in total thickness with the same amount of steel as in my Falk. If you can find such a pan, the Falk would still perform better in terms of evenness in that scenario though, copper has higher thermal diffusivity.
If you somehow start considering a Falk, my advice is to stop at 24cm for the frypan, or you will be sorry. The Falks are so much larger bottomed pans, the 24cm Falk has similar bottom as a 28cm de Buyer. It’s a good size for 21cm induction.
If you would like a slightly larger bottomed pan than the French, and are considering a 28cm frying pan, my recommendation for your cooktop would be Lagostina Accademia Lagofusion. As 7mm total bottom thickness hybrid clad/disc pan, it heats evenly and has a great heat retention, while still providing some sidewall heat.
I have it, and it was my main pan on the cooktop similar to yours. I also have it in 24cm, and that is fantastic on 18cm sidehobs. Now I’m using larger frypans on my 28cm hob, and the 28cm Lagostina hasn’t gotten much time any more. I would still use the 28cm, if I need the cooking space in addition to a larger pan I had already chosen. Or if I were to sear a couple steaks and make a pan sauce.
Honestly, if you are after a 28cm frypan for your cooktop, I would advice to skip the ply and go for the Lagostina. You would be enjoying a great heat spread and cooking performance. Here is a little gallery I have about it
https://imgur.com/a/0MPtevs