i have grown both in northern california. Dicksonia is much more cold hardy but grows way slower than Cyathea. Both of them do not like heat/ full sun. I have no experience with humidity since it is very dry here. My Cyathea has survived multiple times below 21 degrees without protection. I would give both a try, they look great planted together.

Hi
I grow both in s. florida so I feel certain they tolerate heat and humidity lol. Main problem is they way outgrow the location. So i usually chop them up after a couple of years and start over . Recently got a elephant ferm Angiopteris evecta. Understand it will get fronds 15/20 feet and it's not even a tree lol
I'd give them a shot but after winter ebbs ?? Good luck gary

Gary, where did you buy your Angiopteris evecta? I'd love to have one! Please email me if you can tell me where to buy one. Thanks!

Hi
Got the elephant from Gardinos while at the Mounts sale
Another i got from them was a "jade fern" Microsorum thailandicum. Both were very small but VERY hard to locate lol They have an on line catalog?? gary

I like Cyathea cooperi better. But truth be told, I have not had long term success with either. A Dicksonia I purchased started dying soon after I got it despite a position in shade outside in a uniformly humid, rainy summer. Cyathea has lasted longer and should be hardy to your zone. More tolerant of high heat and humidity but low tolerance for any dryness, so water regularly. One missed watering can set it into a decline. Of course, I will try again--always do. Eastern North America is just too extreme in climate for its tastes.