Yes, heat dissipation was a big concern before starting. My MC7455 liked to get quite toasty and I figured the increased power consumption and data rates of the EM91 series would be problematic for heat buildup.
I put my entire project in a small project box with a Noctua 120mm fan pulling air through the enclosure. Sounds like a damn turbine and is probably overkill, but I’d rather be safe than sorry.