AIUI, you won’t be able to store your apps’ data in an “all-SSD” dataset. Unless you use custom apps (aka vanilla docker compose). And even in that case, images themselves would be in the “ix-apps” dataset. And you won’t be able to create “all-SSD” zvol (so no VMs on SSDs).
I am personally a fan of sVDEV, as it provides some form of tiered storage. But this is a very opinionated topic. This thread provides other opinions.
Also, I’m almost 100% sure the benefit isn’t worth the migration headache. Well, strictly speaking, it depends on your use case. Generally, you would get a faster directory listing.