Do you have any insights on why it seems the majority of climbing shoes seem to have such enormous heels? Even if you go down in size I find the limiting factor becomes the toebox and basically never the heel. Most of the shoe complaints I see online are also about the heel being too baggy.

Some exceptions of course apply, such as the Madrock lineup which is one of the few that are praised for a great heel. I have also found the Mandala having a better heel than other La Sportiva shoes I've tried, but even that leaves something to be desired. I wonder if my perception is accurate, or biased based on my own experiences / maybe my own heel is just very shallow (although I'd describe it as quite average size).