Poll usually is run with threads on incoming connections/work, while epoll is keeping conections sleeping and wake up on incoming work. So in which way does this have "nothing to do with threads vs events at all"?

For sure the ratio of sleeping vs. active connections is important in the discussion on node.js model vs. a thread pool with a thread-per-connection setup. If you have very few active connections, poll and a thread-per-connection setup is more efficient (which does say nothing about the ratio of threads per CPU, context switches etc.), if you have a high number of inactive connections, say server-push or chat scenarios, event based connections are more efficient. The OP asked for efficiency.

I don't think the node.js is in any way relevant or efficient for event queues / single thread setups in high throughput scenarios like LMAX where poll/epoll is not relevant. But for node.js, poll vs. epoll setups are highly relevant as they show e.g. node.js vs. standard thread based behaviour.