Carmina's are, from what I was told, more known for their cordovans, than their leathers/suedes. I've only owned suede pairs from Carmina, so I can't personally vouch for how the leathers wear over time. But when I was in their Barca store, the hand on the leathers were very supple and the shoes felt generally well made. The soles wear very well with time, and yep, they get more comfortable as time passes.
I know this wasn't a comparison between Carmina and Meermin (because I don't own Meermins) - apologies for that.
Thanks for the info, very useful! Will check out the Carmina Cordovan options when I get the chance.